Everton manager Frank Lampard is hopeful Dominic Calvert-Lewin will not spend long on the sidelines.
The England forward will miss Saturday's clash at Goodison Park after picking up an injury in training, with Lampard unsure when he will return.
"We are assessing Dom's injury," Lampard said. "No timeframe has been confirmed and we are pretty sure what level it is so we are hopeful it is not long-term.
"We'll miss him for Chelsea. He was looking in great physical condition and was training really well.
"It was a freak injury in training, which does happen. It's a shame but we have to find the solutions to keep ourselves strong without Dominic before he returns."