Everton's season is threatening to go from bad to worse after it was revealed that key midfielder Mikel Arteta has suffered a setback in his recovery from a long-term injury.
The Spanish star, who has been sidelined since February when he suffered a cruciate knee ligament injury, has had to undergo a procedure to remove an infection from the same knee.
Speaking before Thursday's Europa League clash with Benfica, Toffees boss David Moyes said:"Mikel has had to have a 'wash-out' on his knee after doctors found an infection.
"It is a setback for him. However, we can't say how long it has put him back."
The 27-year-old sustained the injury in the opening minutes of last season's goalless draw at Newcastle United and had to leave the pitch on a stretcher.
He endured surgery on his right knee in his homeland in February and was originally expected to be out of action for six months.