Chelsea had two players sent off in a 1-0 defeat at Queen Park Rangers on Sunday that left Andre Villas-Boas' team six points behind Premier League leader Manchester City in the title race.
Heidar Helguson put QPR ahead from the penalty spot after being fouled by David Luiz before the visitors' discipline deserted them ahead of the break in a fiery London derby at Loftus Road.
Portugal defender Jose Bosingwa was the first Chelsea player to receive a straight red card, for pulling back Shaun Wright-Phillips when the winger was through on goal in the 33rd.
Didier Drogba was given the same treatment by referee Chris Foy four minutes before halftime after a two-footed lunge on Adel Taarabt.
It was third-place Chelsea's second defeat of the season.