West Ham United striker Andy Carroll is set to be out for six to eight weeks after suffering knee
Carroll is currently on loan from Liverpool, and has already missed a month of the season with a hamstring injury.
The news will be a bigger blow as the striker scored his first goal for the club last weekend against Spurs.
Allardyce told BBC Sport: "It's pretty severe. We didn't expect it to be quite as severe.
"It's going to be about six to eight weeks. It's a blow for us and Andy."
Having already missed a month due to a hamstring injury suffered against Fulham in September, Carroll had netted only once in 10 games for the Hammers.