West Ham & Wales' Jack Collison ruled out until 2011

Collison has not fully recovered after cartilage damage last season

West Ham and Wales midfielder Jack Collison will be out for around nine months after undergoing knee surgery.

The 21-year-old never fully recovered from the cartilage damage he suffered last season and has not played since Wales' 1-0 defeat to Sweden on 3 March.

"He had an operation and they told me he is going to be out for nine months," said Hammers manager Gianfranco Zola.

"I know he is a strong fellow and I am sure he will be quicker than that. I wish him a quick recovery."

Zola has given the highest praise to the young midfielder, a product of the West Ham youth system, in the past.

His loss will be a severe blow to Wales manager John Toshack, whose other young, star, midfielder Aaron Ramsey is not expected back until 2011 after suffering a horrific leg break when playing for Arsenal.

In the shorter term, Wales look particularly short in midfield for their 23 May friendly in Croatia, Joe Allen (shoulder) having been added to their injury list this week.

The 22 May Championship play-off at Wembley takes precedence over the Croatia match and there are Wales internationals in the squads of all four semi-final contenders.

Cardiff City have Joe Ledley, Adam Matthews and Darcy Blake in their ranks, while their opponents Leicester have the in-form Andy King.

Rob Earnshaw and Chris Gunter feature for Nottingham Forest whose play-off opponents Blackpool have Neal Eardley, David Vaughan and Rob Edwards in their ranks.

Wales captain Craig Bellamy is also unlikely to be considered for the Croatia trip as he is expected to be visiting his footballing foundation in Sierra Leone.