Arvydas Novikovas' late equaliser gave Hearts a deserved draw that dents Dundee Utd's hopes of securing a place in the Champions League qualifiers.
Willo Flood's superb, low 30-yard drive found the far corner of the Hearts net after 32 minutes at Tannadice.
Rudi Skacel steered home a header to equalise three minutes later.
Gary Mackay-Steven fired United ahead after 65 minutes, but substitute Novikovas powered in a second equaliser with seven minutes remaining.
Novikovas celebrates his equaliser for Hearts at Tannadice
It prevented United recording a sixth straight win over Hearts - and a clean sweep this season - and moving ahead of Motherwell on goal difference before the third-top side's meeting with St Johnstone later in the afternoon.
United had gone into the game having won four of their last give games, while Hearts' own chances of European qualification had been dented by their three-game winning streak being ended by Rangers last weekend.
Garry Kenneth had recovered from a hamstring injury to replace Gavin Gunning, who suffered a shoulder problem last week, in a United defence that displayed some early uncertainty.
United goalkeeper Dusan Pernis clutched fresh air with his attempt to a gather at a corner and Ryan McGowan's header flew just over the crossbar.
Play was soon swinging from end to end and Jon Daly's 12-yard header forced the first save from Hearts keeper Jamie MacDonald.
The visitors suffered a blow when Craig Beattie was forced out of action after 29 minutes with a heel injury that has troubled the striker in recent weeks.
Stephen Elliott, who had been replaced with Suso in the starting line-up, was the replacement, the pre-match injury doubt having been dropped to the bench by manager Paulo Sergio.
Hearts were still reorganising when they found themselves a goal behind following Flood's first goal of the season.
McGowan's aimless clearing header had given the midfielder the space to shoot from long range, but the young versatile Australian made amends by providing the cross that immediately led to the equaliser.
Robbie Neilson's clearing header fell to Skacel, who guided the ball off his forehand across the goal and into the far corner from 14 yards for Hearts' first goal in this season's four meetings between the sides.
McGowan's busy few minutes were concluded with a clash of heads with Daly, with the Hearts defender returning to the field with a bandage wrapped round his bleeding brow.
Visiting winger Andrew Driver was fortunate to escape even a booking with the kind of high tackle on Paul Dixon that not only left the United man with a painful shin but has led to many a red card this season.
Hearts also finished the first half the more dangerous in terms of chances and began the second half the better too, with Pernis calmly clawing away a fine curling Danny Grainger free-kick and Marius Zaliukas heading just over from the resulting corner.
Pernis did well to parry a one-handed Skacel header that looked to have initially wrong-footed the goalkeeper following a Driver cross.
United regained the lead against the run of play when Scott Robertson dummied Flood's low corner and Mackay-Steven's bundled shot slipped through the legs of Zaliukas and inside the back post.
Hearts substitute David Templeton fired against the crossbar after a quick break by Suso, but Novikovas' fine strike gave Hearts the equaliser after turning inside Robertson.
A Rankin shot on the turn whizzed past a Hearts post as United had to settle for a point to remain adrift of Motherwell.
Full Time The final whistle goes and the game is over.
Willo Flood takes the free kick.
90:00 +2:25 Booking
Booking Andy Webster goes into the book for unsporting behaviour.
Andy Webster challenges Gary Mackay-Steven unfairly and gives away a free kick.
Shot from just outside the box by Suso Santana misses to the right of the target.
Free kick awarded for an unfair challenge on Paul Dixon by Arvydas Novikovas. Free kick taken by Dusan Pernis.
John Rankin takes a shot from a just insdie the penalty area and hits the post.
Stephen Elliott challenges Paul Dixon unfairly and gives away a free kick. Direct free kick taken by Dusan Pernis.
82:48 Goal scored
Goal! - Arvydas Novikovas - Dundee U 2 - 2 Hearts Goal scored by Arvydas Novikovas from the edge of the area to the top left corner of the goal. Dundee Utd 2-2 Hearts.
Substitution Johnny Russell goes off and Richie Ryan comes on.
Substitution Andrew Driver leaves the field to be replaced by Arvydas Novikovas.
Shot by David Templeton.
Willo Flood takes a inswinging corner to the near post, Stephen Elliott makes a clearance.
Sean Dillon takes the direct free kick.
Booking Suso Santana goes into the referee's book.
Free kick awarded for an unfair challenge on Robbie Neilson by Suso Santana.
Corner taken by Willo Flood played to the near post.
Suso Santana concedes a free kick for a foul on Paul Dixon. Free kick taken by Paul Dixon.
Daniel Grainger takes the outswinging corner, Headed effort from inside the box by Andy Webster misses to the right of the target.
Daniel Grainger takes the inswinging corner, Scott Robertson makes a clearance.
Substitution David Templeton is brought on as a substitute for Ryan McGowan.
Unfair challenge on Marius Zaliukas by Jon Daly results in a free kick. Jamie MacDonald takes the direct free kick.
The assistant referee signals for offside against Stephen Elliott. Indirect free kick taken by Dusan Pernis.
Handball decision goes against Rudi Skacel. Direct free kick taken by Dusan Pernis.
Corner taken right-footed by Ian Black.
Foul by John Rankin on Ian Black, free kick awarded. Free kick taken by Daniel Grainger.
Assist by Willo Flood.
64:06 Goal scored
Goal! - Gary Mackay-Steven - Dundee U 2 - 1 Hearts Gary Mackay-Steven gets on the score sheet with a goal from the edge of the penalty box to the bottom left corner of the goal. Dundee Utd 2-1 Hearts.
Corner taken right-footed by Willo Flood from the right by-line,
Ian Black concedes a free kick for a foul on Johnny Russell. Robbie Neilson restarts play with the free kick.
Rudi Skacel takes a shot. Fantastic save by Dusan Pernis.
Ian Black decides to take a short corner.
Corner taken left-footed by Daniel Grainger from the left by-line, clearance made by Scott Robertson.
Unfair challenge on John Rankin by Suso Santana results in a free kick. Willo Flood restarts play with the free kick.
Foul by Jon Daly on Daniel Grainger, free kick awarded. Jamie MacDonald restarts play with the free kick.
Outswinging corner taken by Ian Black from the right by-line, Headed effort from deep inside the penalty area by Marius Zaliukas goes harmlessly over the crossbar.
Free kick awarded for a foul by John Rankin on Suso Santana. Daniel Grainger produces a shot on goal direct from the free kick, save by Dusan Pernis.
The referee blows for offside against Johnny Russell. Free kick taken by Jamie MacDonald.
Free kick awarded for an unfair challenge on Robbie Neilson by Suso Santana. Free kick taken by Dusan Pernis.
John Rankin has an effort at goal from the edge of the box that misses to the right of the target.
Direct free kick taken by Andy Webster.
Booking Garry Kenneth booked for unsporting behaviour.
Free kick awarded for an unfair challenge on Stephen Elliott by Garry Kenneth.
The second half begins.
45:00 +3:25 Half time
Half Time The players leave the pitch at half time.
Rudi Skacel is ruled offside. Sean Dillon restarts play with the free kick.
Free kick awarded for an unfair challenge on Sean Dillon by Stephen Elliott. Direct free kick taken by Dusan Pernis.
Jon Daly concedes a free kick for a foul on Marius Zaliukas. Jamie MacDonald takes the direct free kick.
Suso Santana concedes a free kick for a foul on Gary Mackay-Steven. Free kick taken by Paul Dixon.
Right-footed shot by Darren Barr went wide of the left-hand post.
Paul Dixon fouled by Andrew Driver, the ref awards a free kick. Willo Flood restarts play with the free kick.
34:47 Goal scored
Goal! - Rudi Skacel - Dundee U 1 - 1 Hearts Rudi Skacel scores a headed goal from inside the area. Dundee Utd 1-1 Hearts.
Johnny Russell provided the assist for the goal.
31:40 Goal scored
Goal! - Willo Flood - Dundee U 1 - 0 Hearts Willo Flood scores agoal from 35 yards to to the bottom left corner of the goal. Dundee Utd 1-0 Hearts.
Paul Dixon produces a strike on goal direct from the free kick.
Booking Booking for Marius Zaliukas for unsporting behaviour.
Willo Flood fouled by Marius Zaliukas, the ref awards a free kick.
Substitution (Hearts) makes a substitution, with Stephen Elliott coming on for Craig Beattie.
The referee blows for offside. Dusan Pernis takes the free kick.
Paul Dixon has an effort at goal from long range that misses to the right of the target.
Free kick taken by Dusan Pernis.
Booking Darren Barr is cautioned.
Handball by Craig Beattie.
Unfair challenge on Craig Beattie by Paul Dixon results in a free kick. Ian Black takes the direct free kick.
The offside flag is raised against Jon Daly. Andy Webster takes the indirect free kick.
Free kick awarded for an unfair challenge on Suso Santana by John Rankin. Jamie MacDonald takes the direct free kick.
Rudi Skacel is caught offside. Dusan Pernis restarts play with the free kick.
Corner taken left-footed by Daniel Grainger, Robbie Neilson makes a clearance.
Andrew Driver takes a shot. Robbie Neilson gets a block in.
Centre by Willo Flood, Johnny Russell takes a shot. Comfortable save by Jamie MacDonald.
Inswinging corner taken from the left by-line by Daniel Grainger, Gary Mackay-Steven manages to make a clearance.
Craig Beattie takes a shot. Clearance by Garry Kenneth.
Darren Barr gives away a free kick for an unfair challenge on Scott Robertson. Willo Flood sends in a cross, Jon Daly takes a shot. Comfortable save by Jamie MacDonald.
Johnny Russell fouled by Andy Webster, the ref awards a free kick. The ball is sent over by Paul Dixon, Sean Dillon has a headed effort at goal from deep inside the area missing to the left of the target.
Scott Robertson delivers the ball.
Foul by Daniel Grainger on Johnny Russell, free kick awarded. Free kick crossed right-footed by Robbie Neilson from right wing.
Unfair challenge on Andy Webster by Jon Daly results in a free kick. Free kick taken by Andy Webster.
Corner taken by Daniel Grainger from the right by-line, Headed effort from close range by Ryan McGowan goes wide left of the target.
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