Substitute striker Didier Drogba equalised eight minutes from time to give Chelsea a 1-1 draw at home against Birmingham City and extend their unbeaten run in the Premier League to 23 matches on Saturday.
Uruguayan Walter Pandiani's 65th-minute strike for the visitors had threatened to end Chelsea's unbeaten home run of 33 matches in all competitions going back to last season.
Chelsea's lead was cut to 11 points with six games to go as second-placed Arsenal won 1-0 at Middlesbrough with a 73rd minute Robert Pires goal.
Chelsea have 81 points from 32 games to Arsenal's 70, while third-placed Manchester United, who are on 67, were playing at bottom club Norwich City later in the day.
Bolton Wanderers kept up their challenge for England's fourth Champions League berth next season with a 3-1 home win over 10-man Fulham, whose Claus Jensen was sent off for a deliberate handball.
Fifth-placed Liverpool's 1-0 defeat at Manchester City allowed Bolton to move within one point of them and just two points behind fourth-placed Everton who are at home to Crystal Palace on Sunday.
Frenchman Alain Perrin celebrated his debut as Portsmouth manager with a 4-2 home win over Charlton Athletic that eased their relegation worries with only their second victory in 13 league games.
Southampton's relegation worries deepened, however, with a 3-0 defeat away against Blackburn Rovers. Saints remain outside the relegation zone only on goal difference.
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