West Ham United midfielder Jack Collison has been ruled out for nine months after undergoing knee surgery.

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

Hammers boss Gianfranco Zola said: "He had an operation the other day and they told me is going to be out for nine months.

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