Bent joined Sunderland for an initial fee of £10m in July 2009
Tottenham's Champions League ambitions were hit by Darren Bent who scored twice in an amazing contest.
The former Spurs striker smashed home a rebound with just 34 seconds gone, and added a penalty for his 23rd goal of the season after Kyle Walker handled.
Incredibly Bent also saw two penalties saved by Spurs keeper Heurelho Gomes.
Anton Ferdinand had an effort ruled out, substitute Peter Crouch headed Spurs back in contention but Boudewijn Zenden's stunning volley sealed it.
Many Spurs followers believed the formidable run of matches against Chelsea, Arsenal and Manchester United would decide their fate in their quest to break into the top four for the first time in the Premier League.
Bent has been a 'revelation' - Bruce
But that was to ignore a trip north to face opponents they had not beaten in four previous visits to the Stadium of Light, with Sunderland losing only once in their last 15 home league matches.
It was perhaps inevitable that Bent, discarded by Spurs last summer, would be fired up for this one, but he managed to inspire his team-mates to greater heights as well in an electrifying start by the home side.
The absence of Jonathan Woodgate, Ledley King and Michael Dawson left a huge void in the Tottenham defence and there was certainly plenty of space as another former Spur Fraizer Campbell swooped to meet Kieran Richardson's corner.
Gomes kept out the point-blank header but it fell perfectly for Bent, who became Tottenham's record signing when he joined them for £16.5m from Charlton in June 2007.
The 26-year-old, who scored 25 goals in 79 games for the Lilywhites, 36 of which were as substitute, rammed home the close-range rebound emphatically and took great delight in celebrating the fastest Premier League goal of the season in front of the travelling Spurs contingent.
With the visitors unable to find any foothold in the game, Jordan Henderson jinked through into the area and fell under a challenge from Benoit Assou-Ekotto but the penalty shouts were waved away by referee Lee Mason.
But when a cross brushed Walker's arm midway through the half the referee did point to the spot for the first time, and Bent confidently beat Gomes low to his right.
Sunderland were simply first to every loose ball, Lee Cattermole had no grievance against Spurs but he snapped at the heels of former Wigan team-mate Wilson Palacios throughout.
Campbell wriggled clear of the attentions of Sebastien Bassong and Assou-Ekotto and burst into the box, before going over an appalling forward's challenge from Luka Modric, who simply hung out a leg.
Bent opted to put the ball to the left of Gomes this time, but the Brazilian leapt across goal magnificently to tip the ball away.
Redknapp refuses to blame ref for loss
Not surprisingly, Harry Redknapp made two changes at half-time, Jermain Defoe and Niko Kranjcar brought on for Assou-Ekotto and David Bentley.
Defoe was soon bursting through on goal but a tame effort was kept out by Craig Gordon.
With Spurs beginning to look more threatening going forward, Gareth Bale's glancing header from a Modric corner was smartly tipped over by the Scottish keeper and Defoe hooked another effort inches wide.
Any momentum the visitors might have been building was halted by another rash challenge, this time by Palacios on David Meyler.
Bent, who missed a penalty on his return to White Hart Lane in November when Spurs beat Sunderland 2-0, struck his third spot-kick of the afternoon to the right of Gomes, but the Tottenham keeper tipped the ball on to the inside of the post and was relieved to grab the rebound.
Ferdinand looked to have sealed it when he calmly sidefooted a loose ball into the bottom corner after a cross from the third former Tottenham player in the Sunderland starting line-up, the influential Steed Malbranque, caused yet more problems.
Goals against Spurs 'meant everything' - Bent
However, referee Mason ruled that Campbell was holding down Gomes in the melee.
Crouch replaced the enigmatic, and on this occasion ineffective, Roman Pavlyuchenko, and the England striker scored with his first touch when he rose to meet Kranjcar's looping cross from the left.
But there were several chances for the home side to make the game safe, substitute Kenwyne Jones completely missing his kick in front of goal and Zenden seeing two efforts blocked.
It seemed as though Spurs might be reprieved and make Sunderland pay for their profligacy, but the final key moment in this astonishing game came from Zenden, who acrobatically volleyed into the top corner following Henderson's looping cross.
The goal would have been cheered as loudly by Liverpool, Manchester City and Aston Villa followers as the race for the coveted fourth place took another twist, with City moving above Spurs in the Premier League thanks to a 6-1 win over struggling Burnley 6-1 in the evening match.
Sunderland manager Steve Bruce:
"I have never, ever, thought we would be involved in a relegation battle - I don't know what all the fuss is about.
"We have got to try to catch Stoke and Blackburn. At the moment, where I see us is arguably third off top in our league.
"That's got to be the aim, to finish as high as we can in our league.
"We could all pick our top eight, but we have got to get Sunderland in and around that 10th position, and that's what we will aim to do."
Spurs boss Harry Redknapp:
"It's still wide-open, we just need to get one or two players back, that's our problem.
"From the neutral's point of view, it was probably a great game.
"They (Sunderland) were up for it today - they don't play like that every week, do they?
"But today, they were full of it. They chased every ball, they pressed, they worked - they played very well today. Full credit to Sunderland."
90:00+4:32 The ball is crossed by Anton Ferdinand, Younes Kaboul manages to make a clearance.
90:00+3:25 Foul by Wilson Palacios on Lee Cattermole, free kick awarded. Craig Gordon takes the direct free kick.
90:00+0:09 Michael Turner gives away a free kick for an unfair challenge on Niko Kranjcar. Eidur Gudjohnsen shoots direct from the free
kick, Craig Gordon makes a save.
88:04 Substitution Fraizer Campbell leaves the field to be replaced by Phillip Bardsley.
87:54 The ball is sent over by Eidur Gudjohnsen.
87:46 Luka Modric sends in a cross, save by Craig Gordon.
87:25 Luka Modric takes a short corner.
85:12 Assist on the goal came from Jordan Henderson.
85:12 GOAL - Boudewijn Zenden:Sunderland 3 - 1 Tottenham Boudewijn Zenden finds the back of the net with a goal from deep inside the penalty box to the top right corner of the goal.
Sunderland 3-1 Tottenham.
84:21 Gareth Bale delivers the ball, save by Craig Gordon.
83:21 Gareth Bale challenges Fraizer Campbell unfairly and gives away a free kick. Boudewijn Zenden delivers the ball from the free
kick left-footed from right channel.
81:53 Corner taken by Niko Kranjcar from the left by-line, Peter Crouch gives away a free kick for an unfair challenge on Michael
Turner. Direct free kick taken by Craig Gordon.
81:41 Luka Modric has an effort at goal. Paulo Da Silva gets a block in.
80:34 Kieran Richardson produces a cross.
80:13 Inswinging corner taken left-footed by Boudewijn Zenden played to the near post.
79:57 Boudewijn Zenden produces a drilled right-footed shot from 12 yards. Younes Kaboul gets a block in.
78:42 Free kick awarded for an unfair challenge on Luka Modric by Kenwyne Jones. Direct free kick taken by Heurelho Gomes.
77:17 Free kick crossed by Kieran Richardson, clearance by Younes Kaboul.
77:17 Substitution Darren Bent goes off and Kenwyne Jones comes on.
77:17 Substitution Boudewijn Zenden on for Steed Malbranque.
77:17 Darren Bent fouled by Younes Kaboul, the ref awards a free kick.
74:08 Kieran Richardson concedes a free kick for a foul on Kyle Walker. The free kick is swung in right-footed by Niko Kranjcar.
73:42 Effort from 18 yards by Fraizer Campbell. Sebastien Bassong gets a block in.
73:08 Jermain Defoe is caught offside. Craig Gordon takes the indirect free kick.
Correction - 72:05 The ball is sent over by Luka Modric,
72:05 The ball is delivered by Luka Modric,
Correction - 71:48 The assist for the goal came from Niko Kranjcar.
71:48 The assist for the goal came from Luka Modric.
71:48 GOAL - Peter Crouch:Sunderland 2 - 1 Tottenham Peter Crouch grabs a headed goal from close in. Sunderland 2-1 Tottenham.
71:36 Corner taken right-footed by Niko Kranjcar from the left by-line, Paulo Da Silva makes a clearance.
71:22 Eidur Gudjohnsen takes a shot. Blocked by David Meyler.
70:56 Inswinging corner taken by Luka Modric from the left by-line played to the near post, Paulo Da Silva manages to make a clearance.
70:02 Substitution Roman Pavlyuchenko goes off and Peter Crouch comes on.
68:42 The ball is crossed by Gareth Bale, Craig Gordon makes a save.
68:30 The ball is delivered by Kyle Walker, clearance made by Michael Turner.
67:22 Free kick awarded for a foul by Sebastien Bassong on Anton Ferdinand. Craig Gordon takes the direct free kick.
66:30 Niko Kranjcar takes the free kick.
66:30 Booking The referee cautions Steed Malbranque for unsporting behaviour.
66:22 Steed Malbranque challenges Kyle Walker unfairly and gives away a free kick.
65:30 Corner taken right-footed by Steed Malbranque to the near post, Darren Bent takes a shot. Save made by Heurelho Gomes.
64:04 Steed Malbranque concedes a free kick for a foul on Heurelho Gomes. Free kick taken by Heurelho Gomes.
63:38 The ball is crossed by Jordan Henderson, clearance by Sebastien Bassong.
62:59 Gareth Bale gives away a free kick for an unfair challenge on David Meyler. The free kick is swung in right-footed by Jordan
60:21 Power penalty taken by Darren Bent saved by Heurelho Gomes. Sunderland 2-0 Tottenham.
60:21 Foul by Wilson Palacios on David Meyler, Penalty awarded.
59:00 Luka Modric takes the chance to get an effort at goal. Save by Craig Gordon.
55:58 The ball is delivered by Kieran Richardson.
55:21 Younes Kaboul gives away a free kick for an unfair challenge on Steed Malbranque. Direct free kick taken by Kieran Richardson.
54:36 Free kick awarded for a foul by Fraizer Campbell on Kyle Walker. Heurelho Gomes restarts play with the free kick.
53:54 Jermain Defoe produces a volleyed right-footed shot from deep inside the penalty box which goes wide of the left-hand post.
51:39 Roman Pavlyuchenko produces a cross, Craig Gordon makes a save.
50:29 Shot from just outside the box by Wilson Palacios goes over the bar.
50:15 Short corner worked by Luka Modric.
49:44 Corner taken by Luka Modric from the left by-line to the near post, Gareth Bale takes a shot. Save by Craig Gordon.
49:37 The ball is delivered by Gareth Bale, clearance by Steed Malbranque.
49:19 Jermain Defoe takes a shot. Save by Craig Gordon.
48:38 Fraizer Campbell is caught offside. Heurelho Gomes takes the direct free kick.
47:25 Kieran Richardson decides to take the corner short, Centre by Jordan Henderson.
46:59 Jordan Henderson produces a cross, clearance made by Wilson Palacios.
46:01 Anton Ferdinand crosses the ball, clearance by Niko Kranjcar.
45:01 The second half kicks off.
45:01 Substitution Jermain Defoe joins the action as a substitute, replacing David Bentley.
45:01 Substitution Niko Kranjcar is brought on as a substitute for Benoit Assou-Ekotto.
45:00+3:14 The first half comes to an end.
45:00+2:46 Kieran Richardson takes a inswinging corner to the near post, Eidur Gudjohnsen makes a clearance.
45:00+2:41 The ball is crossed by Jordan Henderson, clearance made by Benoit Assou-Ekotto.
45:00+1:42 Free kick awarded for a foul by Benoit Assou-Ekotto on Steed Malbranque. Free kick crossed left-footed by Kieran Richardson,
clearance by Eidur Gudjohnsen.
45:00+0:52 Luka Modric challenges David Meyler unfairly and gives away a free kick. Direct free kick taken by Anton Ferdinand.
44:59 Jordan Henderson delivers the ball, clearance by David Bentley.
44:17 Effort from 20 yards by Steed Malbranque. Save by Heurelho Gomes.
42:42 Roman Pavlyuchenko challenges Paulo Da Silva unfairly and gives away a free kick. Craig Gordon takes the free kick.
42:22 The assistant referee signals for offside against Darren Bent. Free kick taken by Heurelho Gomes.
41:02 Inswinging corner taken from the right by-line by Kieran Richardson, clearance by Kyle Walker.
40:09 Penalty taken by Darren Bent is saved by Heurelho Gomes. Sunderland 2-0 Tottenham.
40:09 Luka Modric concedes a Penalty for a foul on Fraizer Campbell.
38:39 Eidur Gudjohnsen takes a shot. Save made by Craig Gordon.
38:27 The ball is delivered by David Bentley, Anton Ferdinand manages to make a clearance.
37:34 Shot from just outside the box by Roman Pavlyuchenko goes over the crossbar.
36:18 Centre by Kyle Walker.
34:45 Free kick taken by Younes Kaboul.
34:45 Booking Lee Cattermole receives a yellow card.
34:38 Lee Cattermole challenges Wilson Palacios unfairly and gives away a free kick.
34:06 David Meyler takes a shot. Blocked by Younes Kaboul.
33:50 Anton Ferdinand produces a cross, clearance made by Kyle Walker.
32:56 Headed effort on goal by Fraizer Campbell from inside the penalty box misses to the right of the target.
32:32 David Bentley challenges Steed Malbranque unfairly and gives away a free kick. Direct free kick taken by Kieran Richardson.
31:21 Centre by David Bentley, Fraizer Campbell manages to make a clearance.
30:22 Free kick awarded for a foul by Darren Bent on Benoit Assou-Ekotto. Heurelho Gomes takes the free kick.
28:38 The assist for the goal came from Steed Malbranque.
28:38 GOAL - Darren Bent:Sunderland 2 - 0 Tottenham Placed penalty scored by Darren Bent. Sunderland 2-0 Tottenham.
28:12 Handball by Kyle Walker.
27:47 Steed Malbranque takes a shot. Heurelho Gomes makes a save.
27:11 The ball is crossed by Kieran Richardson.
25:53 Free kick awarded for a foul by David Meyler on Gareth Bale. Free kick taken by Luka Modric.
25:09 The ball is sent over by Gareth Bale, David Bentley takes a shot. Save by Craig Gordon.
22:44 Wilson Palacios fouled by Lee Cattermole, the ref awards a free kick. Free kick taken by Younes Kaboul.
21:28 Roman Pavlyuchenko concedes a free kick for a foul on Steed Malbranque. Free kick taken by Craig Gordon.
20:04 Lee Cattermole challenges Luka Modric unfairly and gives away a free kick. Direct free kick taken by Younes Kaboul.
19:45 Centre by Fraizer Campbell, Sebastien Bassong manages to make a clearance.
19:34 Anton Ferdinand crosses the ball, Sebastien Bassong manages to make a clearance.
18:32 Steed Malbranque has a drilled shot. Save by Heurelho Gomes.
16:32 Foul by Steed Malbranque on Wilson Palacios, free kick awarded. Direct free kick taken by Sebastien Bassong.
16:00 Roman Pavlyuchenko gives away a free kick for an unfair challenge on David Meyler. Craig Gordon takes the direct free kick.
15:29 Darren Bent concedes a free kick for a foul on Younes Kaboul. Younes Kaboul restarts play with the free kick.
14:40 Centre by Roman Pavlyuchenko.
13:22 Free kick awarded for a foul by Lee Cattermole on Wilson Palacios. Direct free kick taken by Heurelho Gomes.
10:51 The referee blows for offside. Free kick taken by Craig Gordon.
10:26 Darren Bent challenges Wilson Palacios unfairly and gives away a free kick. Wilson Palacios takes the direct free kick.
3:39 Kieran Richardson challenges Kyle Walker unfairly and gives away a free kick. Direct free kick taken by Heurelho Gomes.
3:25 Gareth Bale crosses the ball.
0:36 Assist on the goal came from Fraizer Campbell.
0:36 GOAL - Darren Bent:Sunderland 1 - 0 Tottenham Darren Bent gets on the score sheet with a goal from inside the six-yard box low into the middle of the goal. Sunderland 1-0
0:14 Inswinging corner taken left-footed by Kieran Richardson played to the near post, Fraizer Campbell takes a shot. Save by Heurelho
0:00 The referee starts the match.
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