London :Chelsea missed the chance to go seven points clear at the top of the Premier League when it was held to a 0-0 draw at Birmingham on Saturday.
Chelsea created a handful of second-half chances but has now won just one of its past five Premier League matches, and that only with a late penalty against last-place Portsmouth.
The Blues are now five points clear of defending champion Manchester United, which could trim the deficit to two with victory at Hull on Sunday _ when third-place Arsenal hosts fourth-place Aston Villa.
Tottenham drew 0-0 at Fulham on Saturday, while West Ham beat Portsmouth 2-0.
Birmingham was unlucky not to be ahead at halftime against a Chelsea side featuring Daniel Sturridge in attack alongside Didier Drogba.
Birmingham striker Christian Benitez was called for a contentious offside when through on goal and then had a goal ruled out by a decision from the same linesman. The referee ruled out his close-range finish for offside, even though Drogba was playing everyone on by lying on the floor apparently injured.
Chelsea's best effort came right at the end of the first half when central defender Alex smashed a 35-meter (yard) free kick against the post.
Chelsea coach Carlo Ancelotti eventually replaced Sturridge with Salomon Kalou in the 68th minute and the Ivory Coast striker, playing his last match before he and Drogba depart for the African Cup of Nations, wasted a pair of chances within two minutes.
He miskicked when totally unmarked and then had a shot saved by goalkeeper Joe Hart.
Nicolas Anelka is already out injured and Chelsea's attacking options for Monday's game against Fulham were further reduced when Florent Malouda was sent off for a second yellow card late on. The France international will be suspended.
Mark Schwarzer earned Fulham a point with a late double save, stopping Peter Crouch's long-range volley and blocking Jermaine Jenas's effort on the rebound, but Tottenham's Heurelho Gomes was the busier goalkeeper at Craven Cottage.
Fulham had the better chances all game and the Brazilian 'keeper was forced into two stellar second-half stops by Bobby Zamora, one of three former Tottenham players in the Fulham lineup.
Gomes scrambled across goal in the 63rd to palm away Zamora's downward header at the near post before making an even more acrobatic stop seven minutes later, keeping out another header with a diving save in mid-air.
Fulham's United States international Clint Dempsey had earlier shot wide, hit a 25-meter (yard) free kick against the bar and almost set up a chance with a back-heel flick toward goal.
Damien Duff almost won it for Fulham when he shot wide just two minutes from the end.
West Ham won for the first time in five games through a first-half penalty by Alessandro Diamante, awarded for a foul on on-loan midfielder Luis Jimenez by former West Ham player Hayden Mullins, and late goal by Radoslav Kovac.
Liverpool was hosting Stoke later in another of Saturday's eight Premier League matches.