FC Twente are sweating on the fitness of star midfielder Orlando Engelaar.
The 28-year-old had an exploratory operation earlier this week on his knee and is now set to be ruled out for around two weeks.
During the operation Engelaar had his knee cleaned up and he should be back soon.
"It is an injury I already had for some time but I was able to play on with," said Engelaar.
"A check-up in hospital showed that there was something."
Meanwhile, the Dutch international is continuing talks over a new contract as Twente look to tie him down for another three years.
A number of clubs, including Ajax, have showed an interest but Twente are hopeful of sealing his signature on a new deal.
"Just like we extended the contract of Karim El Abmadi until 2011, it was also our intention to do so with Engelaar," said Twente chairman Joop Munsterman.
"I think that we are in such an advanced stage that I can say he has extended his contract until 2011."