London - Frank Lampard scored from the penalty spot to restore Chelsea's three-point lead in the Premier League with a 2-1 home win against bottom club Portsmouth on Wednesday.
Champions Manchester United had pulled level on points on Tuesday after beating a second-string Wolverhampton Wanderers 3-0 in manager Alex Ferguson's 900th league game in charge.
Arsenal failed to match the pace, held 1-1 by a spirited Burnley at a rain-lashed Turf Moor to move ahead of Aston Villa on goal difference in third place with a game in hand but eight points off the lead.
Chelsea have 40 points, United 37 and Arsenal 32.
Chelsea, without injured top scorer Didier Drogba, dominated from the start at a chilly Stamford Bridge against opponents led by their own former manager Avram Grant, who was given a warm welcome by the home fans.
Nicolas Anelka put the Blues ahead midway through the first half, slotting the ball into the bottom right corner past goalkeeper Asmir Begovic who started as a replacement for unwell David James.
Portsmouth refused to give in and were rewarded five minutes after the break when Jamie O'Hara's free kick hit the wall and fell for Frederic Piquionne to smash the equaliser into the roof of the net.
With Chelsea looking in danger of squandering another opportunity after failing to kill the game off in the first half, Lampard stepped up to lash home the 79th minute penalty.