Cenk Tosun will undergo knee surgery next week after returning to Everton from his loan at Crystal Palace due to injury.
The Turkey striker suffered the problem in training with Palace, and appears unlikely to return to his loan at Selhurst Park, with Everton confirming he will have his subsequent rehab at their Finch Farm training ground.
The knock also reportedly brings in to doubt a potential permanent switch to the South London club in the summer, with an option to buy having been inserted in the loan when he joined on January 10.
"Sometimes not everything goes as you want in life," he tweeted on Thursday. "But; the important thing is not to fall on the ground, but to stand up after falling down. No one should doubt that I will return from this injury in the strongest possible way."
Tosun, 28, made his debut against Arsenal - his first of five appearances for Palace.
He scored in the subsequent draw at Manchester City but has failed to register since in appearances against Southampton, Newcastle and Brighton.
Tosun joined Palace because he wanted more playing time as he bids to win back a place in Turkey's squad for European Championships this summer.
He joined Everton from Besiktas for £27m two years ago but had scored just 10 goals in 51 appearances.
Tosun's arrival at Selhurst Park saw Connor Wickham join Championship club Sheffield Wednesday on loan until the end of the season.