Liverpool midfielder Dietmar Hamann has been ruled out of action until November because of a shin injury.
The German international underwent surgery on the problem earlier this summer and it was thought the injury had cleared.
But Liverpool today confirmed the injury had flared up again and that Hamann (29) underwent an operation in Germany last night.
Manager Gerard Houllier said: "It is a blow for the player and for the club. Things like this show why it is so important we have a strong squad."
With Steven Gerrard suspended for the opening match against Chelsea, Houllier will be sweating over a midfield pairing to compete with the rejuvenated Stamford bridge side.
Senegalese midfielder Salif Diao looks favourite to take the place of Hamann if he recovers from knee ligament damage on schedule. Another option would be Bruno Cheyrou who has impressed in pre-season.
Danny Murphy leads the queue, ahead of new boy Anthony Le Tallec and Igor Biscan, to replace Gerrard whose suspension stems from his sending off against Chelsea in last season's final game.
It is a massive blow for Hamann, who has recently spoke of the new belief that is evident in the squad and of his hopes of pushing for the title.
"It's been our target to win the league for the last few seasons now and we haven't done it, " he said.
"But I think the squad we have now is the strongest its been since I've been here at the club and I think it is good enough to win the league.
"We had a very good chance to win the Premiership two years ago when we finished second with 80 points. I think we were unlucky that year."
Meanwhile Harry Kewell, a stg£5million buy from Leeds, is back in training after an ankle problem and could be involved in the Amsterdam tournament, which begins on Friday.
He was injured in only his second warm-up game for Liverpool and forced to go off against Crewe.
He had taken a knock on the same ankle during the club's training camp in Switzerland. But Kewell decided to tough it out only to suffer a recurrence against the First Division side.