Chelsea suffered a dispiriting 1-0 loss at home to Bournemouth as a late Dan Gosling goal secured all three points for the visitors to end their five-match losing streak and condemn the London side to a fourth defeat in five Premier League games.
Gosling, making his first start of the season, was left alone as Chelsea`s defence rushed out and he looped a shot high over goalkeeper Kepa Arrizabalaga in the 84th minute.
Although the linesman raised his flag for offside, referee Graham Scott awarded the goal after a lengthy VAR check.
Chelsea remain fourth with 29 points from 17 games, while Bournemouth rose to 14th on 19, four points above the relegation zone after their third win in five visits to Stamford Bridge.
The hosts looked off the pace after qualifying for the Champions League knockout stages with a nervy 2-1 home win against Lille on Tuesday.
They had over 60% possession and buzzed around the penalty area to create chances for Tammy Abraham, Mason Mount and Christian Pulisic but struggled to create clear opportunities against a side missing several key players through injury.
Cherries` keeper Aaron Ramsdale pulled off fine reaction saves in each half from midfielder Mount and full back Emerson to keep the south-coast side in the game before Gosling`s goal delighted the travelling fans on a chilly afternoon.
Chelsea coach Frank Lampard said the defeat, after recent losses to West Ham United and Everton, was a reality check for his young players who had racked up a string of wins earlier in the season with attack-minded football.
"If we`re not at our best, if we`re not able break teams down that are organised... then we need to find another way," he said, dismissing suggestions from a reporter that a flat mood among the home fans contributed to the loss.
"Some responsibility is on the players to excite them, to have the personality and the balls to take the ball in an area and beat someone or play forward," said Lampard who suggested this week he wanted a striker in the January transfer window.
By contrast, Bournemouth coach Eddie Howe was full of praise for his team`s battling spirit.
"That`s the best we`ve fought, the best we`ve competed, the most desire I`ve seen from the group," he said.