Everton boss Frank Lampard admits Abdoulaye Doucoure has a hamstring injury.
The midfielder was forced off during defeat at Aston Villa.
Lampard said, "Doucoure has a hamstring injury that we will assess in the next few days. It wasn't a sudden ping, it was more of a tightness - so we will see.
“[Losing Doucoure was significant] because in two games we've had injuries and had to use a sub in the first half [Ben Godfrey was hurt in the opening half against Chelsea].
“You can't call that, but when you have to make a change it can obviously affect the team, no matter who you are losing or bringing in.
“It was an important factor - not the factor, but an important one."