Liverpool striker Fernando Torres will visit a specialist to assess the full extent of the knee injury which forced him to miss Sunday's 0-0 draw with Fulham.
Torres, the Reds' top scorer with 22 goals this season, has been struggling with the problem for several weeks and boss Rafael Benitez confirmed his star forward will go for specialist advice about the injury.
The 26-year-old scored twice in Thursday's 4-1 Europa League win over Benfica despite the injury, but couldn't play through the pain barrier again on Sunday.
Torres was sidelined for a month after a knee operation in January. "He has a problem with his knee and has gone to see a specialist," said Benitez. "We are waiting for news. He had a problem before and we were trying to protect him."
Benitez was criticised when he substituted Torres with 25 minutes remaining at Birmingham last week with the score 1-1, but the injury could now force the former Atletico Madrid star to miss the forthcoming Europa League semi-final against his old club.
There is no indication yet whether Torres's participation in the FIFA World Cup is also under threat.