Chelsea old boy Shaun Wright-Phillips stunned his former club with a 78th-minute winner as bottom side Queens Park Rangers shocked the European champions 1-0 in the Premier League.
The 31-year-old on Wednesday drove home from the edge of the box at Stamford Bridge to move Harry Redknapp's side to within five points of safety and prevent Chelsea from reclaiming third place from Tottenham Hotspur.
"They worked their socks off and they got their rewards. We deserved it and it was a fantastic performance," said QPR manager Redknapp.
"They have set the standard tonight and to get out of this mess, they have to do it every week."
Newcastle United had announced earlier in the day that they had accepted a bid for striker Demba Ba from Chelsea and last season's Champions League winners looked like they needed the extra firepower against their London rivals.
Interim coach Rafael Benitez made five changes to his starting line-up, with Ashley Cole, Ramires, Juan Mata, Eden Hazard and the injured Petr Cech dropping out, and the changes were to prove costly.
Punishment arrived with 12 minutes to play, when Adel Taarabt teed up Wright-Phillips to find the bottom-left corner from 20 yards and bring Chelsea's four-game winning run to a juddering halt.
Everton in top gear
Meanwhile, Everton bolstered their bid for Champions League football by coming from behind to win 2-1 at Newcastle.
Papiss Cisse did his best to prove there is life after his Senegal team-mate Ba by heading Newcastle into a second-minute lead after goalkeeper Tim Krul's long kick was allowed to bounce on the edge of the visitors' box.
Leighton Baines produced a goal-of-the-season contender to equalise, however, rippling the net with a magnificent 30-yard free-kick that left Krul grasping at thin air. Substitute Victor Anichebe completed the comeback on the hour, tapping in Nikica Jelavic's low cross barely ninety seconds after coming on to send Everton up to fifth.
Liverpool reinvigorated their push for European football by sweeping Sunderland aside 3-0 at Anfield to climb two places to eighth. Raheem Sterling opened the scoring in the 19th minute.
Luis Suarez added a second in the 26th minute, and then made it 3-0 seven minutes into the second half.