Joint Bundesliga leaders Hamburg have been dealt a blow with the news that midfielder Romeo Castelen has sustained a new knee injury.
The 26-year-old midfielder suffered the injury while playing for the reserves in the 1-0 defeat against Hallescher FC last weekend.
The player joined Hamburg at the start of the 2007/8 campaign but has missed out for much of that time after twice needing knee surgery.
He could now be out for several more weeks if he needs surgery once again.
Castelen told Bild: "I have been hit on the joint, probably I will need to have surgery.
"Should this become necessary, I will be out for several weeks.
"I am very sad - I was just on my way back from these knee injuries."
Hamburg have several other first team players on the injury list, including defenders Bastian Reinhardt and Alex Silva, midfielder Collin Benjamin and strikers Paolo Guerrero and Mladen Petric.
In light of such injuries, midfielder Ze Roberto has called on the club to strengthen in the January transfer window to help sustain their challenge at the top of the table.
The Brazilian told Hamburger Morgenpost newspaper: "We are having the best ever start to the campaign, we are still undefeated, but we need to be careful.
"Actually, we cannot change the situation - we have some young and inexperienced strikers well worth to be given their share of time (on the pitch) and help by the experienced players also.
"But we need to keep our eyes on the goals of the club - if you want to qualify for the UEFA Champions League, you probably need to buy again this winter.
"This does not mean I am not trusting those players available, but we need to acknowledge there have been long-term injuries to regular players of the first team, again and again.
"This needs to be faced by the management."