Fernando Torres may not be fit in time for Spain's opening World Cup clash with Switzerland, according to Liverpool's new medical chief.

Torres is recovering from a second operation in three months to repair damage in his right knee and, although his rehabilitation is going well, Liverpool's head of sports medicine, Peter Brukner, has warned Spain that their star striker could miss the Group H opener against the Swiss in Durban on June 16.

"He's doing well and he's certainly tremendously committed to his rehab, as are the staff here, and if anyone can recover from an injury, he can," Brukner told Liverpool's website.

"You can't be absolutely certain of anything but at this stage, if he continues to progress the way he is, he should be fit to play at some stage during the World Cup.

"Whether he'll be fit for the first game (on June 16) or not is uncertain."

Reigning European champions Spain are among the favorites for the World Cup, but Torres's absence would be a major blow to coach Vicente del Bosque's plans.

Brukner, who will be working at the World Cup with Australia before taking up his full-time position with Liverpool, said: "We're anxious not to hurry him along too much because we want the long-term benefit, but we're aware he's got the short-term goal of playing in the World Cup.

"Hopefully, we can get a compromise between those two where he plays in the World Cup and he's fit and well for Liverpool next season."