Wayne Rooney put the Red Devils on top in the 53rd, but Robin Van Persie's equalizer in the 83rd for Arsenal was followed by Thierry Henry's game-winner with just seconds left.

The loss is especially tough to take for United, considering that they were just 10 minutes away from taking a nine-point lead over Chelsea in the Premiership standings. Now, Sir Alex Ferguson's men are in for a dog fight over the final 14 games of the season with just a six-point cushion.

Arsenal meanwhile, get a big boost from the win, their second in as many games over United this season. The Gunners have a five-point lead over Bolton for the fourth and final Champions League spot, and are just one point behind Liverpool for third.

The first half was filled with intensity and hard tackles but precious little in the way of scoring chances. The best chance for Arsenal came in the 33rd minute when Emmanuel Adebayor carried the ball down the right wing and crossed perfectly for Henry. However, the Frenchman failed to get maximum power behind the header and United keeper Edwin Van der Sar saved comfortably.

United turned up the pressure in first-half stoppage time and forced Arsenal keeper Jens Lehmann to make a pair of quality stops to keep the game knotted at 0-0.

Lehmann first punched a cross from the left wing clear, but the ball only made it as far as Rooney, who was positioned 25-yards from goal. The English striker then brought the ball down and fired a half-volley that was headed for the top corner of the net, forcing Lehmann to narrowly tip the ball over the bar. The ensuing corner kick also produced a good chance for United, as Ryan Giggs bent a cross into the box that Henrik Larsson headed towards the lower- right corner of the net. Lehmann once again was up to it and made a nice sprawling stop to keep it out.

The Red Devils carried that momentum into the second half and found themselves in front eight minutes after the restart. Cristiano Ronaldo played a ball down the left flank to Patrice Evra, who sent a cross towards the front of the net. The ball took a slight deflection off Arsenal defender Kolo Toure and found Rooney at the back post. The striker then headed the ball past Lehmann to give United a 1-0 lead.

Midway through the half, Arsenal boss Arsene Wenger brought on a pair of attack-minded players in Robin Van Persie and Julio Baptista in an effort to level the match. The move paid off 10 minutes from time.

The Gunners found the equalizer as Tomas Rosicky took control of the ball on the right wing and drove it into the box. Henry then played the ball on with a neat heal-flick and found Van Persie charging towards the back post. The Dutch striker finished the play by hammering the ball into the roof of the goal from close range to even the match.

With the two teams headed for a share of the points, Henry grabbed all three for Arsenal in the dying moments. A cross from Emmanuel Eboue found Henry just inside the penalty spot. This time, Henry got plenty of power behind his header and knocked it just past the outstretched hand of Van der Sar, sending the Emirates stadium into a state of frenzy.

In Sunday's other fixture, Mikel Arteta scored twice to lift Everton past Wigan 2-0 at the JJB Stadium.