Chelsea teen Billy Gilmour is facing four months out with a knee injury.
The Scot broke down during victory at Crystal Palace.
"Billy Gilmour had an operation on his knee this morning, so out for maybe 3-4 months," the Chelsea boss Frank Lampard confirmed.
"I am disappointed, as is he. I spoke with him yesterday and giving him support.
"He is a tough boy, but he should be pleased with what he has done this season. His attitude will get him back as soon as he can.
"His character for me is fantastic, especially with his age. He will put in the work and the rehab. We will be there for him."