Watford closed in on the play-off zone with a third successive victory that dented Cardiff City's promotion push.
Peter Whittingham gave Cardiff a lead with a delicate curling shot just after Danny Graham missed a penalty for the hosts following a foul on Will Buckley.
But Graham made amends when he levelled as the striker fired in Buckley's ball.
Marvin Sordell's long-range hit put the Hornets ahead before a John Eustace header and a successful Graham penalty gave dominant Watford a deserved win.
The home side, who beat Championship leaders Queens Park Rangers in their previous fixture, followed that impressive result by defeating the side placed second in the division.
It was the Bluebirds' heaviest loss of the season - their fourth in their last six games - and resulted in their manager Dave Jones finding his side seven points adrift of QPR, who won 2-0 at Coventry.
Watford should have enjoyed a bigger victory over a side missing star strike duo Craig Bellamy and Jay Bothroyd. But Hornets boss Malky Mackay saw his men miss an early spot-kick.
Visiting left-back Lee Naylor clipped winger Buckley's legs inside the box and referee Mark Haywood had no hesitation at awarding the blatant penalty.
Malky Mackay hails 'complete' Watford display
But Cardiff keeper David Marshall made a stunning save diving to his right to keep out Graham's fierce penalty.
And within ten minutes the Bluebirds were ahead against the run of play as Peter Whittingham guided in his fifth goal of the season.
Chris Burke set up the former England under-21 international and he curled the ball beautifully, with his left foot, around keeper Scott Loach and into the bottom right hand corner.
Graham, though, quickly made amends for his penalty miss as the Watford striker fired in the equaliser.
A misplaced Naylor header inadvertently set-up Buckley and Watford's flying winger crossed for Graham to convert from close-range.
Buckley was giving Naylor a torrid time down Watford's right flank - so much so that Jones saved the full-back from his struggles and replaced him with teenager Adam Matthews.
It was Matthews' Cardiff defensive team-mate Darcy Blake, however, who was lucky not to concede another penalty just before the break when Graham sent Sordell into the box.
The Watford forward was hacked down by Wales international Blake inside the penalty area but referee Haywood waved away the home side's protests.
But Watford did take the lead 11 minutes into the second-half and it was Sordell's first goal in two months that punished the Bluebirds.
Dave Jones bemoans 'worst display'
His left-footed drive from the edge of the penalty area clipped the inside of Marshall's post before nestling into the back of the net.
And Watford's second goal in six minutes finished off Cardiff.
Captain Eustace's fifth goal of the season - a glancing close-range near-post header from Don Cowie's left-hand corner - secured Mackay's men their first win over Cardiff in six games.
Cardiff provided little in the way of attacking guile or endeavour and Michael Chopra's delicate curling shot from the edge of the area was all that Loach had to do other than picking Whittingham's opener out of the net.
The Bluebirds were not up to much defensively either as Watford's quick and elusive attack tormented - and the hosts rammed home their advantage with a late penalty.
Again it was the outstanding Buckley that won another penalty and when he bundled over by Cardiff captain Mark Hudson.
Graham had the nerve to step up again and he sent his second spot-kick of the afternoon straight down the middle to move Watford to within a point of the play-offs with his fifth goal in three games and 14th of the season.
Live text and stats
Tuesday, 28 December 2010
Graham (pen) 84
03 A Taylor yellow card
05 M Taylor
11 Buckley (Jenkins 90+2)
18 Mutch (Walker 90+2)
10 Graham (Massey 90+2)
03 Naylor yellow card (Matthews 35)
10 McPhail (Koumas 76)
11 Burke (Rae 73)
Ref: HaywoodAtt: 14,560
Attempts on target
Attempts off target
90:00+5:14 The final whistle is blown by the referee.
90:00+5:02 Adam Matthews delivers the ball, clearance by Lloyd Doyley.
90:00+4:41 Gavin Massey takes a shot. Blocked by Mark Hudson.
90:00+1:39 Substitution Josh Walker on for Jordon Mutch.
90:00+1:39 Substitution (Watford) makes a substitution, with Ross Jenkins coming on for Will Buckley.
90:00+1:39 Substitution (Watford) makes a substitution, with Gavin Massey coming on for Danny Graham.
90:00+0:12 Kevin McNaughton takes a long range shot clearing the crossbar.
88:36 The offside flag is raised against Andrew Keogh. Scott Loach restarts play with the free kick.
86:38 The ball is sent over by Will Buckley, Mark Hudson manages to make a clearance.
83:15 Mark Hudson concedes a Penalty for a foul on Will Buckley. Assist on the goal came from Will Buckley.
83:15 GOAL - Danny Graham:Watford 4 - 1 Cardiff Danny Graham scores a penalty. Watford 4-1 Cardiff.
81:09 Danny Graham is caught offside. Indirect free kick taken by Mark Hudson.
76:56 Jordon Mutch crosses the ball, save by David Marshall.
76:07 Inswinging corner taken left-footed by Peter Whittingham played to the near post, Marvin Sordell makes a clearance.
75:45 Substitution Stephen McPhail goes off and Jason Koumas comes on.
75:19 Michael Chopra takes a shot. Scott Loach makes a save.
72:05 Substitution Gavin Rae comes on in place of Chris Burke.
68:12 Lloyd Doyley fouled by Andrew Keogh, the ref awards a free kick. Lloyd Doyley takes the free kick.
65:29 Lloyd Doyley challenges Kevin McNaughton unfairly and gives away a free kick. David Marshall restarts play with the free kick.
63:08 Corner taken by Don Cowie from the left by-line played to the near post, assist on the goal came from Don Cowie.
63:08 GOAL - John Eustace:Watford 3 - 1 Cardiff John Eustace finds the back of the net with a headed goal from close in. Watford 3-1 Cardiff.
62:39 Marvin Sordell takes a shot. Mark Hudson gets a block in.
59:45 Corner taken by Jordon Mutch from the left by-line, clearance by Mark Hudson.
59:04 Chris Burke produces a cross, clearance by Martin Taylor.
58:17 A cross is delivered by Will Buckley, Darcy Blake makes a clearance.
56:53 GOAL - Marvin Sordell:Watford 2 - 1 Cardiff Marvin Sordell finds the net with a goal from the edge of the penalty area to the bottom right corner of the goal. Watford
55:48 The ball is delivered by Peter Whittingham, John Eustace manages to make a clearance.
54:12 Free kick awarded for a foul by Don Cowie on Chris Burke. Free kick taken by Stephen McPhail.
53:48 Andrew Taylor sends in a cross, save by David Marshall.
52:00 Jordon Mutch produces a right-footed shot from just outside the box that misses to the right of the target.
51:37 Chris Burke sends in a cross.
Correction - 50:52 Don Cowie delivers the ball, Kevin McNaughton manages to make a clearance.
50:52 Don Cowie delivers the ball, Adam Matthews manages to make a clearance.
49:16 Chris Burke produces a right-footed shot from outside the penalty box and misses right.
49:01 Centre by Andrew Keogh, Don Cowie manages to make a clearance.
48:30 Chris Burke challenges Lloyd Doyley unfairly and gives away a free kick. Andrew Taylor takes the free kick.
47:24 The ball is swung over by Will Buckley.
46:43 Marvin Sordell takes a shot. Save by David Marshall.
46:15 The ball is delivered by Kevin McNaughton, clearance made by Andrew Taylor.
45:01 The second half begins.
45:00+2:15 The half-time whistle blows.
45:00+0:43 Marvin Sordell takes a shot. David Marshall makes a save.
44:12 A cross is delivered by Danny Graham.
42:56 Marvin Sordell takes a shot. Save by David Marshall.
42:24 Peter Whittingham gives away a free kick for an unfair challenge on Will Buckley. Don Cowie restarts play with the free kick.
39:15 Corner taken right-footed by Jordon Mutch from the left by-line to the near post, Adrian Mariappa produces a left-footed shot
from close in that clears the bar.
37:17 The referee blows for offside against Andrew Keogh. Free kick taken by Scott Loach.
35:43 Jordon Mutch challenges Peter Whittingham unfairly and gives away a free kick. Strike comes in from Peter Whittingham from
the free kick, blocked by Martin Taylor.
Correction - 34:33 Free kick awarded for a foul by Andrew Taylor on Chris Burke. David Marshall takes the free kick.
Correction - 34:33 Substitution Adam Matthews replaces Lee Naylor.
34:33 Andrew Taylor gives away a free kick for an unfair challenge on Chris Burke. David Marshall restarts play with the free kick.
34:33 Substitution Adam Matthews comes on in place of Lee Naylor.
34:33 Booking Booking for Andrew Taylor.
30:21 Free kick awarded for an unfair challenge on Will Buckley by Lee Naylor. Direct free kick taken by Adrian Mariappa.
30:21 Booking Booking for Lee Naylor.
27:06 Free kick awarded for a foul by Marvin Sordell on Seyi Olofinjana. David Marshall takes the free kick.
26:57 A cross is delivered by Don Cowie, clearance made by Seyi Olofinjana.
26:41 Jordon Mutch crosses the ball, clearance by Seyi Olofinjana.
23:40 Assist on the goal came from Will Buckley.
23:40 GOAL - Danny Graham:Watford 1 - 1 Cardiff Danny Graham scores a goal from close range to the top left corner of the goal. Watford 1-1 Cardiff.
22:54 Michael Chopra is ruled offside. Scott Loach takes the indirect free kick.
22:08 The ball is sent over by Lloyd Doyley.
21:06 The ball is delivered by Will Buckley.
19:07 Will Buckley is caught offside. David Marshall takes the free kick.
18:45 Michael Chopra takes a shot. Blocked by Adrian Mariappa.
17:48 The assistant referee flags for offside against Marvin Sordell. David Marshall takes the indirect free kick.
16:37 Andrew Keogh delivers the ball, Scott Loach makes a save.
15:10 Chris Burke provided the assist for the goal.
15:10 GOAL - Peter Whittingham:Watford 0 - 1 Cardiff Peter Whittingham gets on the score sheet with a goal from the edge of the penalty box to the bottom right corner of the goal.
Watford 0-1 Cardiff.
12:40 Lee Naylor concedes a free kick for a foul on Will Buckley. Free kick crossed right-footed by Don Cowie from right wing, clearance
made by Kevin McNaughton.
11:26 Free kick awarded for a foul by Lloyd Doyley on Michael Chopra. Direct free kick taken by Lee Naylor.
10:08 Will Buckley produces a cross, clearance by Darcy Blake.
8:06 The official flags Michael Chopra offside. Scott Loach takes the indirect free kick.
7:16 Free kick awarded for a foul by Marvin Sordell on Lee Naylor. Direct free kick taken by David Marshall.
6:49 Placed penalty taken by Danny Graham saved by David Marshall. Watford 0-0 Cardiff.
5:46 Lee Naylor challenges Will Buckley unfairly and gives away a Penalty.
5:26 Will Buckley sends in a cross, Seyi Olofinjana manages to make a clearance.
5:03 Jordon Mutch decides to take the corner short, The ball is crossed by Will Buckley, David Marshall makes a save.
4:47 Centre by Marvin Sordell, Mark Hudson gets a block in.
3:26 The ball is crossed by Danny Graham, Jordon Mutch has a header from close range and clears the crossbar.
2:27 Effort on goal by Jordon Mutch from long distance goes over the crossbar.
1:37 The ball is crossed by Chris Burke, John Eustace manages to make a clearance.
0:23 Will Buckley takes a shot. Save made by David Marshall.
0:00 The match has kicked off.
Live text and data provided by The Press Association.
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