Everton midfielder Jack Rodwell suffered a suspected hamstring injury as an experimental Toffees side slipped to a 1-0 Europa League defeat by BATE Borisov.
Everton, their place in the next round already assured, lost 1-0 after David Moyes selected a young team including five debutants in the starting XI.
Rodwell was forced to come off in the eighth minute and limped to the touchline after appearing to catch his studs in the turf.
He seemed to be in some distress and it was an early blow for the inexperienced Toffees side.
After seeing his side go down to Aleksandr Yurevich's 75th-minute strike, Moyes said: "It looks as though Jack has a hamstring injury.
"We will know more on Friday when he will have a scan. These things happen in football and you have to get on with it."
It means Rodwell is likely to miss the Barclays Premier League match against in-form Birmingham on Sunday and weaken Moyes' hand even more.
Joseph Yobo, Sylvain Distin and Dan Gosling are all injured as well as long-term absentees Mikel Arteta, Phil Jagielka, Phil Neville, Victor Anichebe and James Vaughan.
