Chelsea crashed to a 2-1 loss at Everton on Wednesday and saw its Premier League lead trimmed to a point by Manchester United, which drew 1-1 with Aston Villa.
Louis Saha missed a penalty but still scored twice for Everton after Florent Malouda put Chelsea ahead, with the French striker's goals doing a big favor for former club United, which survived Nani's sending off to earn the point at Villa.
Arsenal recovered from its weekend loss at Chelsea to close the gap on Chelsea to six points as Abou Diaby's second-half strike clinched a 1-0 victory over Liverpool.
At Goodison Park, Chelsea was in control when Malouda scored after 17 minutes by latching onto Didier Drogba's header from goalkeeper Petr Cech's long clearance.
But Louis Saha exposed Chelsea's weakness from setpieces by heading in a 33rd-minute equalizer from Landon Donovan's cross, which dropped over Frank Lampard.
Donovan won a penalty before half time after being clipped in the area by Ricardo Carvalho, but Saha's spotkick was saved by Cech.
But Saha did find the net again in the 75th after connecting with a long ball that was misjudged by Chelsea captain John Terry.
United had Nani sent off for a two-footed challenge on home captain Stiliyan Petrov. The Portugal winger, who has recently been in the best form of his Old Trafford career, is now set to receive a three-match ban that will also rule him out of the Feb. 28 League Cup final against Villa.
The score was already 1-1 when Nani saw red in the 29th minute.
Carlos Cuellar had headed Villa ahead after latching onto Stewart Downing's ball, but United for the 10th time this season benefitted from an own goal.
Nani's cross was volleyed back across goal by Ryan Giggs and James Collins, with Paul Scholes waiting behind him, could only turn the ball past Brad Friedel, who was making his 215th consecutive league appearance in the Villa goal.
A lackluster match at Emirates Stadium was settled by Diaby exploiting a gap in the Liverpool defense to head in Tomas Rosicky's cross. Arsenal survived late scares when Ryan Babel struck the crossbar and Cesc Fabregas appeared to handle Liverpool captain Steven Gerrard's late free kick while in the penalty area.
West Ham and Wolverhampton moved out of the relegation zone with victories and are level on 24 points, one above the drop zone.
Alessandro Diamanti and Carlton Cole scored the goals as West Ham enjoyed a 2-0 victory over Birmingham, whose former owners David Sullivan and David Gold are now in charge at Upton Park.
At Wolves, midfielder David Jones netted his first league goal of the season to clinch a 1-0 victory over sixth-place Tottenham.
Hull is also on 24 points after losing 1-0 at Blackurn.
