Liverpool manager boss Roy Hodgson is worried that Dirk Kuyt will miss more than the suggested four weeks.
The 30-year-old attacker suffered ruptured ligaments in his shoulder while training with the Dutch national team over the weekend and is expected to miss games in the Premier League against Birmingham City, Manchester United and Sunderland.
He is also down to be unavailable for the Carling Cup game against Northampton Town and the Europa League meetings with Steaua Bucharest and Utrecht, however he has expressed his desire to be ready for the latter as the game is against his old club at the end of September.
Manager Hodgson is less positive though, saying of Kuyt’s absence: "It could be more than four weeks.
“It's one of those injuries where it's very difficult for the doctor to say and I think four weeks is a very conservative estimate.
"If we're lucky, it could be earlier, but it could be longer. We have to be very careful because it's the type of injury that has to be treated with a lot of respect.
"It's a great blow for us because Dirk is an important member of our first team. He does a job which is not easy to replace because he has all the qualities required for that role on the field.
"I was very sad to see such a thing happen, especially in a training session.
"He's a quick mender and he has a great mentality and attitude towards recovery, so he will be back as quick as is humanly possible."
David Ngog is also a concern for the Sunday game with Birmingham with a hamstring worry, while defender Fabio Aurelio is defintely out with an Achilles problem.
Hodgson added: "(Ngog)...has been nursing a problem but is much better now.
"I am hoping that he will recover in time for this weekend. We have nursed him through and hopefully he will train either today or Friday.
"Fabio is making very good progress and is definitely moving in the right direction. It was a relatively minor problem but one we had to nip in the bud because Achilles injuries can be very problematic."