England hopeful Gary Cahill could miss the rest of the season after suffering a blood clot in his arm.
The Bolton centre-half had been hoping to win a place in Fabio Capello's World Cup squad but his chances appear over.
Cahill was taken ill on Friday and was admitted to hospital the next day as Bolton drew 0-0 with Fulham.
Manager Owen Coyle said: "Gary suffered a pain in his arm and it became severely swollen. There was no way he could play. It is a severe blow for the boy but our main concern is his welfare. We have to make sure Gary is fit and well.
"He will miss the next few months, it might be for the rest of the season.As disappointed as we are, at 24, Gary has a marvellous career ahead of him. I believe he would have made the World Cup for the summer."
Cahill, who is due to be released from hospital today, was called up by Capello last summer after Rio Ferdinand was forced out of the qualifier against Kazakhstan with a calf injury.
