Florent Malouda's 67th-minute goal moved Chelsea into third spot and ensured Wigan Athletic remain rooted to the foot of the Premier League following a 1-0 defeat at Stamford Bridge.
Carlo Ancelotti's side remain five points clear of fifth-placed Tottenham Hotspur and took one step closer towards securing a place in next season's Champions League.
But this was an unconvincing performance by Ancelotti's side, who struggled in front of goal with 50 million pound record signing Fernando Torres again failing to open his account for the club in a 31-minute substitute appearance.
The Spaniard missed two good chances to score late on and has now gone 648 minutes without a goal for his new club.
Ancelotti had insisted his side's focus would be trained exclusively on this game despite the looming shadow of next week's Champions League quarter-final second leg trip to face Manchester United.
But it was clear that thoughts were already shifting towards Old Trafford with the manager making five changes from the side that lost 1-0 in the first leg three days previously.
Skipper John Terry was given the day off while Torres was held in reserve on the bench -- a sign that Ancelotti wants to field a fresh Torres against United despite insisting before this game player's place was by no means guaranteed in that match.
Having beaten Wigan 8-0 and 6-0 in the previous two meetings, Ancelotti might have been entitled to believe he could field a reserve side against the Premier League's bottom club and still expect to win comfortably.
But those victories were completed at the end of last season and the beginning of this when Chelsea made a habit of thrashing weaker opposition.
Much has changed since the Blues hit the Latics for six at the DW Stadium in August and while Ancelotti's side have emerged from their mid-season doldrums, no one would confidently assert that it is now business as usual.
Confidence remains fragile at the west London club and a convincing victory would have provided Ancelotti's players with a valuable lift ahead of the United clash that could decide their prospects of landing silverware this season.
And when Didier Drogba broke to the byline before pulling back for Frank Lampard to shoot after just 38 seconds, it appeared as though they would have no problem securing the points quickly.
Lampard's shot deflected wide, however, setting the tone for a frustrating first half when Chelsea's finishing once again left much to be desired.
Eight minutes later Drogba was again the provider, slipping in a pass to Florent Malouda, who was unable to find a way past Wigan keeper Ali Al Habsi after shooting with his weaker right foot.
Al Habsi denied Malouda again towards the end of the half - this time with an outstanding one-handed save after the France international had got behind the latest defence to connect with a Drogba flick on.
But in between those opportunities, Wigan forced their way back into the game and showed enough to suggest they could embarrass Chelsea.
Striker Hugo Rodallega in particular was causing the Chelsea backline problems and he turned off David Luiz to create space before seeing his shot deflected over.
The home crowd reacted to Chelsea's failure to get out of second gear with a smattering of boos at the half time whistle as frustration grew.
Ancelotti responded by introducing Yossi Benayoun at the interval for his first appearance since injury an Achilles in September.
But Chelsea's 67th minute breakthrough owed more to a mistake by Al Habsi than any tactical masterplan.
By then Torres had been introduced in place of Nicolas Anelka and it was the Spaniard's presence at a corner that unsettled the keeper, forcing Al Habsi to flap at the ball and Malouda finished from close range.
Torres was desperate to break his duck but Al Habsi twice saved from the Spaniard, the second block an outstanding effort after the striker was sent clear by Benayoun.