Chelsea had Jose Bosingwa and Didier Drogba sent off in the first half, falling to a 1-0 defeat.
London: Chelsea had two players sent off in a 1-0 defeat at Queen Park Rangers on Sunday as Andre Villas-Boas' team lost their discipline to fall six points behind Premier League leaders Manchester City in the title race.
Heidar Helguson put QPR ahead from the penalty spot in the eighth minute after being fouled by David Luiz before the visitors' calm deserted them in a fiery west London derby at Loftus Road.
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 - although John Terry seemed to be covering the Portugal defender.
Didier Drogba was given the same treatment by referee Chris Foy four minutes before half-time after a two-footed lunge on Adel Taarabt.
Chelsea also had seven players booked, but Villas-Boas stuck up for his team, preferring instead to criticize the officials.
"I'm very disappointed with Chris' performance," the Portuguese coach said. "With nine players, we kept our emotions very well. Chris and his team (of officials) managed to play an emotional game and they conceded to the crowd and committed tremendous mistakes."
Villas-Boas added: "The ref was poor, very very poor ... I spoke to him at the end and I was very aggressive to him. I don't care if he's OK or not."
It was third-placed Chelsea's second defeat of the season - and first loss to QPR in 16 years - but the team had only themselves to blame by getting wound up in front of a hostile crowd and in the face of provocation by Joey Barton and his QPR teammates.
"Our boys did fantastically - we had a plan and it worked a treat," said QPR manager Neil Warnock, whose team climbed up to 10th place in the table.
"To get three points against Chelsea is like a dream."
Despite playing more than a half with nine men, Chelsea still had chances to come away with a point.
The best fell to Nicolas Anelka, who headed straight at QPR goalkeeper Paddy Kenny from four yards. England leftback Ashley Cole, one of the players to receive a yellow card, also went close late on.
"I have to praise the players because they were amazing," Villas-Boas said. "For 45 minutes, we played with nine men and that takes courage. It shows the strength and commitment of squad."
Since joining Chelsea from Benfica in January, Luiz has made a name for himself with his attacking forays - scoring three goals in the process - but his defending has not been as impressive.
The Brazil centerback was at fault for the only goal, nudging Helguson over as they competed for the ball following a long clearance.
Chelsea goalkeeper Petr Cech got his fingertips to the penalty but couldn't keep it out, allowing QPR to celebrate their first home win since gaining promotion.