Everton have sent John Stones to see an ankle specialist to try and ascertain the extent of the injury he suffered at Old Trafford on Sunday.
Stones went over awkwardly on his ankle in the closing stages of the game and had to be stretchered off in obvious discomfort, with the club's medical team suspecting ligament damage.
Liverpool Echo writer Greg O'Keefe is reporting that the swelling around Stones injury has yet to subside, making an accurate diagnosis difficult.
The 20-year-old, who has been forced to withdraw from the England squad for matches against San Marino and Estonia this week, is to visit a specialist in the hope of a clearer diagnosis.
Should Stones be told he has torn ankle ligaments then he could be out for around 8-10 weeks, a devastating blow for both the defender and Everton, who are already dealing with a lengthy injury list.
Ross Barkley, Kevin Mirallas, James McCarthy and Seamus Coleman are all currently sidelined with various injuries, so this is an blow Roberto Martinez could really do without.
The club are hoping Stones has merely strained his ligament, which could see him back playing within four weeks. Fingers crossed people.