Liverpool striker Fernando Torres remains a major doubt for Spain's FIFA World Cup opener against Switzerland - but is putting in the hours in a bid to be fit.

The 26-year-old underwent an operation on his right knee last month and is now working six hours a day in a bid to face the Swiss on 16 June. "Right now, we cannot say whether Fernando will be ready in time for the first match against Switzerland," said Spain team doctor Juan Jose Garcia Cota.

"He has started to work outside and is still doing gym work to improve the muscle tone around the knee. It takes a long time but the process we are following is still very good. We cannot say for sure but we are optimistic. There are still many days and the injury evolves day to day."

Torres, who netted the winning goal for his country in the UEFA EURO 2008 final against Germany, was yesterday named in Vicente del Bosque's preliminary 30-man squad. After tackling Switzerland in South Africa, Spain will play further Group H games against Honduras and Chile.