Everton boss Frank Lampard admits Yerry Mina will be missing for two months.
The Colombian went off injured in the 3-1 defeat at Newcastle and Lampard is now facing the prospect of being unable to call upon Mina for as many as 10 weeks.
"Yerry Mina is an unfortunate injury which will probably be between 8-10 weeks," Lampard said.
"In the week I've been here I've realised he is a big leader in the group, a top player, and a big miss. I was aware on the night of how serious it was and our worst fears were confirmed. Yerry's a big personality here, he's a positive man who we'll miss."
Winger Demarai Gray will also miss the crucial trip to Leeds this weekend but Lampard is hopeful his return will come far sooner than that of Mina's.
"Gray won't be fit for Leeds, we're hoping he'll be back for next week," he said.
Delph is a couple of weeks away, but Calvert-Lewin is in the squad for tomorrow."