London:Samir Nasri got Arsenal back in the groove as the French midfielder scored twice to give the Gunners a much-needed 2-1 win against Manchester United on Saturday.
Arsene Wenger's side started as underdogs on their home turf after a miserable run of three games without a win - including a tumultuous meltdown at Stoke - but they produced a superb performance to cast aside doubts over their title prospects this season.
Nasri opened the scoring midway through the first half in a thrilling encounter, then added his fifth goal of the campaign moments after half-time to seal the points.
A last minute goal from Rafael da Silva - his first for United - gave the champions hope, but they couldn't force an equaliser despite six minutes of injury-time.
Arsenal, who moved to within three points of leaders Chelsea ahead of their match at Blackburn on Sunday, are now firmly back in the title race, while United are five points off top spot.
Ahead of kick-off much of the talk had been of Arsenal's injury problems, so relief swept around the Emirates Stadium once the teams were announced with Theo Walcott, William Gallas and Mikael Silvestre coming through fitness tests.
For United there was just one change from the side that beat Hull last time out in the league, Park Ji-Sung coming in to replace Nani on the left of midfield.
Arsenal started nervously and goalkeeper Manuel Almunia gave away a needless free kick within one minute as he handled a Silvestre back pass. The set-piece led to Michael Carrick firing wide for the visitors.
Arsenal had not lost back-to-back league games in 56 outings, but the signs were not looking good as that defeat at Stoke seemed to pray on their nerves early on.
United had a goal ruled out after eight minutes, Bulgarian forward Dimitar Berbatov had strayed offside before slotting home from close range after a Wayne Rooney shot was pushed away.
Wenger's men worked their way into the game and Nicklas Bendtner should have tested goalkeeper Edwin van der Sar with two headed chances before the quarter hour mark.
Arsenal took the lead in the 22nd minute. Patrice Evra fouled Bacary Sagna on the right side of the penalty area.
Cesc Fabregas's free-kick was cleared by Berbatov as far as Nasri on the edge of the box and he hit a left foot shot which deflected off Gary Neville and into the net.
The remainder of the half was tense. Walcott struck a decent opportunity over the crossbar, and Arsenal hearts were in mouths as Gael Clichy's apparent handball from a Rooney cross was not given as a penalty.
After the break Arsenal quickly slipped into gear and doubled their lead.
Fabregas produced a brilliant turn just outside the United area on 48 minutes and slipped in Nasri, who drilled a fine strike beyond the grasp of Van der Sar.
It was a desperate blow to United, the league's in-form team following a run of seven games without defeat.
Yet within a minute they should have reduced the deficit, Cristiano Ronaldo slotting wide from close range following a perfect lofted cross by Park.
Rooney had a header saved soon after, and the visitors then introduced Ryan Giggs in place of Anderson with 18 minutes remaining in a bid to salvage something from the game.
However, it was Arsenal who had the next opportunity, referee Howard Webb waving away penalty appeals as Nemanja Vidic tugged on the shirt of Nasri.
Ferguson brought on Carlos Tevez in place of Rooney in a further bid to snatch an unlikely point and Arsenal were forced to take off Almunia, with Lukasz Fabianski on after the Spanish keeper was injured in a challenge with Carrick.
United teenager Rafael, on for Neville, gave United a glimmer of hope in the 90th minute when he chested down a clearance on the edge of the area and volleyed left footed into the corner of Fabianski's net.
But victory takes Arsenal into third place, and although Man United have a game in hand, this is a huge psychological boost for Wenger and his side.