Ronald Koeman fears that Yannick Bolasie could be sidelined for Everton until 2018.
Bolasie saw the second half of a debut season with the Blues curtailed by a knee ligament injury sustained during last month’s draw with Manchester United.
The DR Congo international underwent surgery on the problem twice and had been expected to face a lengthy lay-off as he recovers from the setback.
Addressing shareholders at the club’s General Meeting, Koeman admitted that Everton may be without Bolasie until the second half of the 2017/18 campaign.
He said: “At the moment, he’s optimistic. It was difficult because it is a long-term injury.
“He will be around 10, 11, 12 months and that is really disappointing.
“First for the player, then for the club and also the manager because he was one of the good signings that the club made this summer.
“But he’s still 27-year-old, he will come back; he has a strong mentality.
“We are looking forward to when he is back on the pitch.”