Everton midfielder Darron Gibson could reportedly miss the club's Premier League opening match against Norwich City.
The 25-year-old was forced off the field in the first half of the Toffees' pre-season victory over Real Betis at the weekend.
It is understood that the Merseyside outfit will assess the knee problem in the coming days in order to learn the extent of the injury, according to the Liverpool Echo.
Meanwhile, manager Roberto Martinez has claimed that Marouane Fellaini will be fit for the trip to Carrow Road, despite being left out of the squad amid rumours that Manchester United are interested in signing the midfielder.