Fulham delivered a stoppage-time hammer blow to Chelsea's Premier League title aspirations with Rodrigo Muniz's last-gasp finish grabbing a 2-1 win and a first victory at Stamford Bridge for the Cottagers since 1979.
Muniz was in acres of space in the box when Sasa Lukic found him with a low cross to deliver a belated Christmas gift to the elated travelling support. The Fulham bench emptied in celebration - Chelsea's subs, coaching staff and boss Enzo Maresca slumped back into their seats.
The Blues head coach has repeatedly tempered talk of a title challenge and, after drawing with Everton at the weekend, this Boxing Day derby defeat leaves them reeling four points adrift of Liverpool who play their first of two games in hand when they host Leicester later.
Sub Harry Wilson - who had turned another west London derby against Brentford with heroics off the bench earlier this season - cancelled out Cole Palmer's wonderful opener with a close-range header and Fulham capitalised on the counter to score a historic victory over their neighbours.
For Fulham - who have taken points off Liverpool, Arsenal and Tottenham this season - this was another landmark moment of their progression under Marco Silva. Hit by injuries to their midfield, they switched to a back five and weren't at their usual ball-playing best for much of the contest. But when they pushed forward after the break they showed the pace and precision to take a big scalp. They finish the day level on points with defending champions Man City and on the brink of the European qualification places.
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Chelsea made one change, with Marc Cucurella back from suspension and in for Axel Disasi.
Fulham went to a defensive five with Joachim Andersen back, Andreas Pereira returning from suspension and Raul Jimenez in to lead the line among five changes.
The visitors should have been level well before Wilson's 83rd-minute intervention but Antonee Robinson's usually trusty touch let him down at the crucial moment and allowed Robert Sanchez to smother the shot. Meanwhile, Fulham 'keeper Bernd Leno also caught the eye with several key stops - particularly late on when he denied Christopher Nkunku and then Jadon Sancho.
Leno also tipped an Enzo Fernandez drive over the bar but after Palmer beat a couple of Fulham challenges and finished sweetly through the legs of Issa Diop and into the bottom corner in the first half, Chelsea's threatening moments were only fleeting.
A Levi Colwill header rightly ruled out for offside at the start of the second half was another - but this perhaps was a performance that backed up Maresca's claims his side are not yet ready to duel for the biggest prizes.
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