Arsenal moved back to second place in the Barclays Premier League after finally beating title rivals Chelsea for the first time since November 2008 with a 3-1 victory at the Emirates Stadium.
The Gunners finally made the breakthrough after 43 minutes. Jack Wilshere and Alex Song exchanged passes on the edge of the area, with the Cameroon midfielder carrying the ball into the box.
Paulo Ferreira slid in and tripped Cesc Fabregas, but Song had the presence of mind not to wait for a whistle and swept a low left-footed shot across goal and into the bottom right corner.
Arsenal, had a two-goal cushion after 51 minutes. Robin van Persie held the ball up 30 yards out, and, as he was closed down, Michael Essien's challenge inadvertently pushed the ball straight to Walcott clean through on goal. The England winger dashed to the edge of the box, where he drew Petr Cech before sliding the ball along to Fabregas and the Arsenal skipper made no mistake from 15 yards.
Chelsea had little chance to recover, as Walcott smashed in goal number three just 90 seconds later. Walcott robbed Florent Malouda and fed Fabregas, who repaid the favour by sending the Arsenal winger away down the right for him to slot a low shot into the bottom left corner.
Chelsea snatched a lifeline after 57 minutes when Drogba's free-kick floated through to the six-yard box, where it was nodded in by Branislav Ivanovic. However the Blues were unable to find a way back as their poor run continued.