Chelsea's recovery under Rafa Benitez was brought to a shuddering halt by Queens Park Rangers on Wednesday as the Premier League's bottom team won 1-0 in the west London derby.
QPR's first win in the topflight at Stamford Bridge since March 1979 was secured by Shaun Wright-Phillips scoring against his former club in the 78th minute.
The end of Chelsea's four-game winning run in one of the biggest shocks so far this season left Benitez's side fourth in the standings.
Everton is only two points behind after beating Newcastle 2-1, but has played a game more than both Chelsea and sixth-place Arsenal.
Liverpool still has its sights on the top four, beating Sunderland 3-0 to move seven points behind Chelsea but having played a match more.