Argentina Football Association (AFA) doctor Homero D'Agostino does not expect Manchester City striker Sergio Aguero to be fit for the World Cup after undergoing a left knee operation.
Aguero aggravated a knee injury during the Manchester derby earlier this month and underwent arthroscopic surgery on Tuesday in Barcelona.
He is set to miss the remainder of the campaign with City but should recover ahead of Argentina's World Cup opener against Iceland on June 16.
"That a player has undergone an arthroscope with 60 days to go before the World Cup is worrying," D'Agostino told Radio 10. "The recovery process will require at least five weeks. When one has old injuries, the recovery process is not as fast as one would like it to be. It's never going to be less than three or four weeks, or even more.
"I imagine that he will not arrive 100 percent fit with the limited time that is left before the World Cup. The anatomy is the anatomy. The injury is what it is. He can try but I don't think he will arrive 100 percent."
City's top scorer this season with 30 goals in all competitions, Aguero missed Argentina's international friendlies against Italy and Spain last month.
He has not started a game since March 4 but made late substitute appearances in the home defeats to Manchester United and Liverpool.
D'Agostino believes surgery was the only option left for Aguero.
"The important thing is to know what he had," he said. "The doctors would have tried to resolve the issue in a conservative manner, non-surgically, but they were unsuccessful. The arthroscopy is a process that you do when there are old injuries."
Aguero's father, Leonel del Castillo, is more optimistic after speaking to his son following the surgery.
"I spoke to Sergio and he is well," Del Castillo told Radio La Red. "He had the surgery in order to arrive in good shape at the World Cup without problems. He is in good spirits. He got hurt during training [on March 11] and then aggravated the injury in the Manchester derby.
"He will remain two or three days in the clinic and then he will spend a further few days recovering [in Barcelona]. He will return to Manchester in eight or nine days. Sergio told me that he will be training in 20 days. Perhaps he could play the penultimate or the last game [for City] but I don't know."
City clinched the Premier League title on Sunday with five games remaining when United lost 1-0 at home to West Bromwich Albion.
Meanwhile, Argentine media have begun debating whether Aguero should be called up by Argentina coach Jorge Sampaoli for the World Cup.