LONDON (AFP) Chelsea opened up a four-point lead at the top of the Premier League after Didier Drogbas double inspired a 2-0 win at Wolves and Everton claimed a 3-1 victory over Manchester United on Saturday. Carlo Ancelottis Chelsea have often dropped points on their travels this season but in-form Drogba, who has six goals in five games since returning from the Africa Cup of Nations, ensured the Blues were able to take advantage of Uniteds slip. In the days early kick-off, United looked lethargic after their mid-week victory against AC Milan and slumped to their first defeat in nine league games. Dimitar Berbatov put Sir Alex Fergusons team ahead in the 16th minute when he controlled Antonio Valencias cross perfectly before smashing a close-range shot past Tim Howard. But Uniteds lead was short-lived as Russian winger Diniyar Bilyaletdinov drove a vicious swerving effort past Edwin van der Sar from 25 yards. United struggled to find any momentum after that and David Moyess team took the lead in the 76th minute. South African midfielder Steven Pienaar whipped over a low cross for substitute Dan Gosling to steer in just his second goal of the season. Jack Rodwell ensured United would suffer their sixth league defeat of the season in the 90th minute as he surged away from Jonny Evans and drove his shot into the far corner. We were well beaten, simple as that, Ferguson said. We started the game well enough, but their goal galvanised them and gave them the incentive. This is a bad result and at this time of the year we cant afford results like that. At Molineux, Chelsea struggled in the early stages but finally pieced together an incisive move to take the lead in the 40th minute. Yuri Zhirkov exchanged passes with Michael Ballack and the Russian crossed for Ivory Coast striker Drogba to slot home. Drogba took his goal total for the season to 25 in the 67th minute when poor defending from Christophe Berra allowed him to reach Petr Cechs long punt, round goalkeeper Marcus Hahnemann and drive in his 25th goal of the season. Ancelotti said: We went into this game knowing we had the chance to improve our position after the Manchester United result. The players were aware United had lost and we managed to take advantage of the situation but nothing is decided at this moment. Third placed Arsenal are just two points behind United after a 2-0 win against Sunderland at the Emirates Stadium. Arsene Wengers team made the breakthrough in the 27th minute when Denmark striker Nicklas Bendtner tapped-in Emmanuel Eboues cross for his first goal since October. Gunners captain Cesc Fabregas stroked home a 90th minute penalty after the Spaniard was bundled over by Fraizer Campbell to leave Sunderland without a win in 11 league matches. West Ham boosted their survival bid with a 3-0 win over fellow strugglers Hull at Upton Park. Gianfranco Zolas team got off to the perfect start as Swiss midfielder Valon Behrami fired home from Guillermo Francos flick in the third minute. Hull midfielder Craig Fagan was sent off for a second bookable offence after tugging Alessandro Diamanti early in the second half. England forward Carlton Cole struck in the 59th minute and Julien Faubert added West Hams third in the 90th minute as the hosts moved four points clear of the bottom three. Bottom of the table Portsmouth are eight points from safety after Salif Diaos stoppage time goal gave 10-man Stoke a 2-1 win at Fratton Park. Avram Grants beleaguered side took the lead in the 35th minute through on-loan striker Frederic Piquionne. But German defender Robert Huth equalised five minutes after half-time with a header from Glenn Whelans corner. Stoke had Andy Wilkinson sent off for a second booking midway through the second half but Senegal midfielder Diao won it with his first Premier League goal for eight years.