Manchester United kept within touching distance of the top of the Barclays Premier League thanks to Danny Welbeck's late goal in a 2-1 win at Arsenal.
United knew they needed a win to keep close to leaders Manchester City and they looked on course for victory when Antonio Valencia nodded home Ryan Giggs' cross.
Arsenal rallied in the second half and pulled one back through Robin van Persie, but their hopes of a point were dashed nine minutes from the end when Welbeck steered Valencia's cross home from close range.
Arsenal made United's task much easier thanks to an abject first-half defensive display from the Gunners' makeshift back four.
In the opening minute of first half injury time Giggs was given space down the left flank and he floated a cross over to the back post where Valencia beat Thomas Vermaelen in the air to nod home.
Arsenal went off at half-time to a chorus of boos and manager Arsene Wenger, clearly unimpressed by Johan Djourou's contribution, replaced the defender with 18-year-old Nico Yennaris who was making his league debut.
Van Persie was presented with an easy chance five minutes after the break when Tomas Rosicky pinched the ball off Chris Smalling and squared for him but he fired wide from 10 yards.
Then with 20 minutes to go, Arsenal stunned the visitors with an equaliser. The Gunners broke through Alex Oxlade-Chamberlain who squared for Van Persie and his reverse shot flew through Jonny Evans' legs and in off the post.
The Emirates Stadium was shocked in to near silence with nine minutes left after Welbeck put the Red Devils ahead.
Valencia lost his marker Arshavin and played a clever one-two with Ji-Sung Park before squaring to Welbeck, who bundled home from close range.