**Chelsea have been forced to replace Cole Palmer minutes before kick-off against West Ham.**
The Blues attacking midfielder was named in the starting XI to take on the Hammers by manager Enzo Maresca.
But he will play no part in the match after suffering an injury in the warm-up.
Palmer left the warm-up after being treated by Chelsea's medical staff at the London Stadium.
He was replaced by winger Estevao Willian, who is making his first Premier League start.
The Brazilian appeared off the bench during Chelsea's 0-0 draw against Crystal Palace on Sunday and produced a lively cameo.
The exact nature of Palmer's injury has not yet been revealed but the nature of his withdrawal will no doubt be a concern for the Blues.
Matters were made worse for Enzo Maresca's side after Lucas Paqueta put West Ham 1-0 up on six minutes with a stunning strike.
The Brazil midfielder carried the ball towards the penalty area and fired it into the top right corner from 25 yards, leaving goalkeeper Robert Sanchez with no chance of saving it.
But they were quickly back on level terms nine minutes later, with Joao Pedro heading home from close range from a corner.
Chelsea's record without Cole Palmer
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Palmer has been Chelsea's star player over the past two Premier League seasons, scoring 37 goals and providing 19 assists.
He played all bar one game last season, and only missed two games the season before.
Coincidentally, two of his absences were due to illness, and saw him miss away fixtures against Arsenal on both occasions.
Sadly for Chelsea, they lost 1-0 and 5-0 to the Gunners at the Emirates Stadium.
His only other absence was enforced, having hit the yellow card threshold before a home fixture against Crystal Palace in December 2023. Chelsea won that match 2-1.