Chelsea regained control of the title race as victory at Old Trafford saw them leapfrog Manchester United at the Premier League summit.Didier Drogba's contentious strike - scored from a clearly offside position with 11 minutes remaining - was the decisive moment as Chelsea established a two-point lead at the top of the table.Drogba only emerged as a late substitute after being left on the bench in favour of Nicolas Anelka, but his priceless strike was a moment of triumph for coach Carlo Ancelotti and perfect reward for his bold tactical move.Joe Cole's clever flick gave Chelsea a well-merited lead after 20 minutes as Sir Alex Ferguson's champions struggled for creativity with injured inspiration Wayne Rooney watching in frustration from the sidelines.Drogba's goal looked to have sealed Chelsea's win, but Federico Macheda's scrambled effort - which also had a hint of handball - set up a grandstand finish in which Rooney's replacement Dimitar Berbatov wasted a glorious chance to equalise.Chelsea, who had the game's outstanding performer in Florent Malouda, have produced the perfect response to their Champions League exit against Inter Milan and a tame draw at Blackburn. Twelve goals against Portsmouth and Aston Villa provided the platform and confidence for what could prove to be a pivotal victory.United looked jaded after their midweek exertions in the Champions League defeat at Bayern Munich and they will rightly be furious at the manner of Drogba's debatable goal, but Chelsea were the more impressive team for long periods and have been swiftly reinstalled as title favourites.Ancelotti created a stir with his starting line-up by keeping Drogba on the bench and retaining the team that thrashed Aston Villa 7-1. He saw his faith reap rich dividends as Chelsea dominated the first 45 minutes.Chelsea were the sharper team in the early exchanges and it was no surprise when they took the lead with a goal that typified their approach.Malouda, a player transformed from the struggles at the start of his Chelsea career, drove deep into United's penalty area and his low cross was cleverly flicked past Edwin van der Sar by Cole.United, with Berbatov isolated, were left frustrated and this was illustrated by Paul Scholes, who was lucky to still be on the pitch after escaping with a late tackle from behind on Deco before being booked for a foul on Malouda.Referee Mike Dean, at the centre of controversy after wrongly awarding Blackburn a penalty at Burnley last Sunday, was in the spotlight again as he waved away spot-kick appeals from both sides.United felt Ji-Sung Park had been fouled by Yuri Zhirkov, while Chelsea believed Anelka had been bundled over by Gary Neville. Dean ignored the appeals, and, in his defence, both incidents were inconclusive.Chelsea were inches away from a second goal shortly after the interval when Cole's perfectly weighted pass played in Paulo Ferreira, but the defender was indecisive in an attacking position and his half-hit effort rolled inches wide.United finally managed to build momentum as the hour approached, and Berbatov stretched to direct Ryan Giggs' cross just off target.Ancelotti responded by shuffling his resources in attack with 20 minutes left, replacing Anelka with Drogba, who was being watched from the stands by new Ivory Coast coach Sven-Goran Eriksson.And he demonstrated what he is all about within 10 minutes of entering the action, albeit in controversial circumstances. He raced on to Salomon Kalou's pass and buried a finish past Van der Sar, but he was at least a yard offside when he received the pass.If Chelsea thought this would pave the way to a comfortable conclusion, they were thinking again inside two minutes as Macheda pulled a goal back for United. He bundled a finish over the line after Petr Cech half-cleared from Nani, although there was a suggestion of handball from the Italian.In a predictably hectic finale, Berbatov should have levelled for United, only to volley Neville's cross straight at Cech.It was the final act of the drama - and the Chelsea celebrations illustrated the significance of these three points.Source: BBC