Liam Miller's 89th-minute goal snatched a point for Sunderland in a thrilling 125th Tees-Wear derby.
Leadbitter notched for Sunderland within two minutes
Sunderland took the lead after 75 seconds when Michael Chopra's shot hit Grant Leadbitter and fell kindly for him to slot past Mark Schwarzer.
Boro equalised when Gary O'Neil's cross was headed in by Julio Arca and then Stewart Downing drilled past Craig Gordon from 25 yards out.
But with time running out Miller fired in a left-foot shot from 20 yards.
Middlesbrough appeared as if they had the game in the bag with Sunderland looking all out of ideas in the last 20 minutes.
But Miller took his half-chance wonderfully to provide a dramatic end to an intriguing battle between the two youngest managers in the Premier League.
Roy Keane's and Gareth Southgate's sides combined to produce a game full of incident.
In the build-up to the game Keane had taken his side to an army assault camp and at times it was like a battlefield at the Riverside.
Middlesbrough were forced to make two changes in the first half an hour as Tuncay Sanli and Arca were forced off with injury.
It all threatened to spill over midway through the second half when local boys Leadbitter and Lee Cattermole came to blows.
Leadbitter had earlier put Sunderland ahead when he profited from a touch of fortune.
He started the move in his own half, found Chopra on the left but then got in the way of his team-mate's shot before reacting well to clip the ball into the bottom corner.
Boro responded quickly, even after losing Sanli to injury, and they equalised on 15 minutes when Arca found O'Neil.
His pinpoint cross picked out the unmarked Argentine at the backpost and his low header beat Gordon at his near post.
Arca, who scored for Sunderland in a 2-0 win when the two teams last met at the Riverside and was such a favourite during his time up the A19, declined to celebrate in front of the visiting fans.
Arca scored against his former club
He was spared any further dilemmas when he was stretchered off after picking up a knock in a clash with Dwight Yorke.
When Jonathan Woodgate and then Mido went down it looked like the home side would have to use all their substitutes by half-time, although both were able to carry on.
O'Neil should have marked his full debut with a goal, while the hobbling Mido headed just over before the break.
The action continued after the interval with Lee Dong-Gook almost curling Boro ahead and then Sunderland having appeals for a penalty when Woodgate handled in the area.
Ross Wallace lashed a left-foot shot just past the upright but Boro deservedly went in front.
The dangerous Downing, who enjoyed a hugely successful loan spell at Sunderland, stepped inside and smacked a right-foot shot that beat Gordon all ends up from 25 yards.
Keane threw on all his available attacking options, but they were unable to make any headway on the Boro goal until Miller's timely intervention.
Middlesbrough manager Gareth Southgate:
"We've come so close but I don't want anyone walking out with their heads down - I'm proud of them.
"They scrapped and battled and stood up to the fight and they have given me absolutely everything.
"We're down because we felt we were that close to winning the game. Anything that could have gone wrong did."
Sunderland manager Roy Keane:
"I didn't enjoy it apart from the last few minutes.
"We never got control of the game. As soon as we scored the first goal we never got possession. We stood back and maybe we lacked a bit of Premier League experience.
"We weren't creating chances or gambling enough but they had that desire to get something. Every point is going to be vital."
Middlesbrough: Schwarzer, Young, Woodgate, Wheater, Taylor, O'Neil, Rochemback, Arca (Boateng 27), Downing, Sanli (Lee 12), Mido (Cattermole 58).
Subs Not Used: Jones, Riggott.
Booked: Boateng, Taylor, Cattermole.
Goals: Arca 15, Downing 67.
Sunderland: Gordon, Halford, McShane, Higginbotham, Collins, Leadbitter, Yorke (Stokes 67), Etuhu (Miller 53), Wallace (O'Donovan 76), Jones, Chopra.
Subs Not Used: Ward, Harte.
Booked: Etuhu, Chopra, Leadbitter, Miller.
Goals: Leadbitter 2, Miller 89.
Ref: Howard Webb (S Yorkshire).