Nigerian international, Henry Onyekuru, faces up to six months on the sidelines with a knee injury.
The 20-year-old signed for the Blues in the summer, but was immediately loaned to Anderlecht for the season.
But there are fears that Onyekuru’s campaign could be over after an injury he picked up against Eupen last week.
It has been reported that Onyekuru has damaged the medial ligament with concerns that tests may actually reveal an anterior cruciate ligament injury.
Anderlecht coach Hein Vanhaezebrouck said: “He is possibly out for six months.”
Should Onyekuru’s injury be as bad as feared then he is almost certain to miss the World Cup in the summer.
It has yet to be confirmed if Onyekuru will do his rehabilitation at Everton or stay in Belgium.
It is a cruel blow for the 20-year-old, who had played in 19 league games and appeared in four Champions League matches for the Brussels outfit.
He was given a run out in Nigeria’s last World Cup qualifier in Algeria in November when he came on in the second half of the 1-1 draw and was hoping to make Gernot Rohr’s final 23-man squad for Russia in June.