BUENOS AIRES, April 18 -- Argentine striker Sergio Aguero will not be fully fit for the start of the World Cup in Russia after undergoing knee surgery, national team doctor Homero D'Agostino said on Wednesday.

Aguero had keyhole surgery on his left knee on Tuesday and his club Manchester City said the 29-year-old would miss the rest of the season.

The former Atletico Madrid player also faces a race against time to be ready for Argentina's first World Cup group match against Iceland in Moscow on June 16, according to D'Agostino.

"I imagine that he will not be 100% at the World Cup given the little time remaining," D'Agostino told Argentine television channel TyC Sports.

He added that Aguero would need another three or four weeks before resuming training.

"The important thing to know is that this was an existing injury," D'Agostino said. "The doctors took a conservative approach by allowing it to heal without surgery but that didn't work."

Aguero, who has scored 30 goals this season, was one of five City players named in the Professional Footballers' Association Premier League team of the year on Wednesday. The others were Kyle Walker, Nicolas Otamendi, David Silva and Kevin De Bruyne.