Liverpool's Spanish forward Fernando Torres is out for the season with a knee injury. ((Andrew Yates/Getty Images) )

Spain's striker Fernando Torres faces a race to be fit for the World Cup after requiring knee surgery that is set to rule him out for six weeks.

The surgery was due to take place Sunday night and will mean he misses the rest of Liverpool's season, the Premier League club announced.

"Fernando saw a specialist in Spain earlier today and it was decided that he would need surgery on a torn cartilage in his right knee," Liverpool said in a statement. "We cannot comment ahead of the operation but, as a guide, the usual rehabilitation period for this type of procedure is around six weeks."

While Torres could be fit for Spain's World Cup opener against Switzerland on June 16, Liverpool will have to cope without him.

Liverpool faces Torres's former club, Atletico Madrid, on Thursday in the Europa League semifinals.