The Manchester City striker remains a doubt for Tuesday's Champions League clash because of a hamstring injury.
The striker has been sidelined with a hamstring injury since Jan. 29, with an initial prognosis of a month on the sidelines. Pellegrini was more upbeat last week, insisting Aguero and Fernandinho were close to a full recovery, but the Argentine is still a major doubt to for the last-16 first-leg clash.
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"It's my opinion that for Aguero it is very difficult," Pellegrini told reporters. "Fernandinho? Maybe if he worked with no problem and today he is 100 percent fit — and if he does not have any fear about his injury — we will see if he can play.
"They have to be 100 percent. If there is any risk of them being injured again, they won't play. We will talk to the doctor and see what happens."
Javi Garcia, meanwhile, returned from injury as City triumped over Chelsea to reach the FA Cup quarterfinals Saturday, and Pellegrini is hoping the result can act as a springboard for player and club.
"I think Javi played a superb game, in all senses — practical, technical," he said. "It’s not easy when you have just come back from injury after two or three weeks out. He is always an important option but at the moment I’m not thinking about what we’re doing on Tuesday. We will see how the players recover."