Frank Lampard has confirmed Everton right-back Nathan Patterson will be out for around six weeks with a medial knee ligament injury.
The Scotland international went off in the second half during the home defeat to Brighton & Hove Albion on Tuesday night, and boss Lampard said a scan has revealed the extent of the injury.
Ahead of Friday's FA Cup third round tie against Manchester United at Old Trafford, Lampard also said Anthony Gordon could return after missing the past two matches through illness, while he will weigh up Dominic Calvert-Lewin's availability as the striker's fitness is monitored following a recent comeback from a knee injury.
Lampard said: "Nathan's out for six weeks, unfortunately. It’s a medial ligament injury.
"It’s a blow for us. He’s a young full-back who’s come in, broke through and done really well for us. We know that.
“Now it’s time for others to take that mantle and he’ll be back in six weeks.
“It seems a long time now but he’ll be back.”
Lampard added: "We’ve had illness with Anthony Gordon and Yerry Mina. Yerry is over it, Anthony is on the back end of it so we’ll have to consider that.
“Dominic is pretty fatigued after the Brighton game, so we have to consider that as well going into the game so we’ll see whether he’s fit to start.
“Other than that I believe we are where we were [before Brighton].”