Valencia have lost Dutch star Hedwiges Maduro for around four months.
The 26-year-old midfielder damaged ankle ligaments in training with Holland last week, and he has now undergone surgery in Amsterdam.
Maduro was expected to be back this year, but he will now not play until 2012.
Jorge Candel, Valencia's chief doctor, confirmed: "The recovery time will probably be longer than we had expected.
"We thought that it might be a two-month injury but we now realise that this could last for up to four months."
Maduro told Voetbal International: "This has come at the wrong time for me.
"I was in good form, playing regularly for Valencia and was back in the Holland squad.
"I am already thinking of having a strong second half of the season. That should be enough to get me to the European Championships.
"I will have to fight and start again from scratch. Much will depend on how I perform for Valencia."