General manager Jerry Reese said Thursday that Manning's left ankle surgery will keep him ''out of spring ball.''
''We will not rush him back,'' Reese said. ''We want him for the summer - that's most important to us.''
Reese also expects Manning to bounce back from a poor season in which he led the NFL with 27 interceptions.
''Eli is a smart guy. I think he's driven to prove last year was just an odd year for him,'' Reese added.
Manning's primary backup last year, Curtis Painter, recently underwent arthroscopic surgery on his right knee and is out for about a month. He could be back for the team's minicamp in June.
Nassib did not throw a pass in his rookie season after the Giants selected him in the fourth round.
''We'll take a real good look at him,'' Reese said. ''He didn't have the chance to play. He'll get a lot of work this spring.''
Reese was far less steadfast on third-year running back David Wilson, who comes off neck surgery. The Giants signed free agent Rashad Jennings away from Oakland, and the veteran entering his sixth NFL season could be the starter.
''David Wilson is really kind of a bonus for us if we can get him back,'' Reese said. ''He's on schedule to be back.''
New York also picked up the fifth-year contract option on cornerback Prince Amukamara, the team's top selection in 2011. That move needed to be made by Saturday.
Amukamara has been inconsistent as a pro and plagued by injuries. The Giants brought in cornerbacks Dominique Rodgers-Cromartie and Walter Thurmond as free agents.
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