Everton midfielder Marouane Fellaini will miss Sunday's Merseyside derby against Liverpool after being ruled out for six weeks with a hamstring injury.
Fellaini picked up the injury during Belgium's Euro 2012 qualifier against Austria in midweek and scans on his return to Merseyside have confirmed the extent of the problem.
"It is a very big blow because he is an important player for us," admitted manager David Moyes.
The 22-year-old midfielder missed the closing months of the last campaign with an ankle injury.
He was injured during a fractious 1-0 derby defeat to Liverpool at Anfield in February following a collision which led to the sending-off of home defender Sotirios Kyrgiakos.
Meanwhile, Moyes has given a more upbeat assessment of defender Phil Jagielka.
Jagielka picked up a hamstring injury while away on England duty this week.
"He is not as bad as we first thought, but it (Sunday's derby) may just come too quick for him," said Moyes. "That is the way it is looking at this moment in time."