Argentinian rugby union star Juan Martin Hernandez faces a race to be fit in time for the World Cup which begins in September after a surgeon said he would be out of action for up to five months.

The 28-year-old underwent an operation on a ruptured right knee ligament in Buenos Aires on Wednesday for an injury he suffered while playing for his French Top 14 club Racing-Metro earlier this month.

"Everything went well. It was a difficult operation and we are now hoping that the body does its work in terms of healing," said the chief surgeon Dr Mario Larrain.

"It will take at least five months for him to be able to resume playing rugby.

"It is still possible that he can play at the World Cup (which runs from September 9 to October 23 in New Zealand) but we have to wait and see how his rehabilitation evolves."

Hernandez, known as the 'Magician' for his inspiring play in the backs whether at fullback, fly-half or centre, has been capped 33 times by Argentina, for whom he was their stand-out performer in the 2007 World Cup where they reached the semi-finals.

However, since then he has suffered a succession of injuries which saw him virtually play no rugby for South African outfit the Natal Sharks in a year with them (2009/10).

After his return to France this season, he was out for over a month with a thigh injury.

Argentina are in Group B at the World Cup and begin their campaign against 2003 winners England on September 10 before playing Romania, Scotland and Georgia.

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