After saying he wasn't worried wide receiver Odell Beckham Jr. was sitting out, Manning said the following about Barkley, according to Pat Leonard of the New York Daily News: "Now Saquon, that's different, just because he's a rookie and missing some valuable time. So I know he's getting mental reps. It's different than practice reps; it's different than game reps. Hopefully he can get back soon."
Barkley hasn't practiced or appeared in a preseason game since straining his left hamstring during practice Aug. 13.
While Giants head coach Pat Shurmur has yet to make an official announcement regarding Barkley's status for Friday's preseason game against the New York Jets, Leonard noted the rookie seems likely to miss his second consecutive contest.
New York selected Barkley with the No. 2 pick in the 2018 NFL draft following his standout collegiate career at Penn State.
In the Giants' preseason opener, Barkley dazzled with 43 yards on four carries, including a 39-yard gain.
Barkley is expected to bring balance to a Giants offense that ranked 26th in the NFL last season with 96.8 rushing yards per game.
With the rookie on the shelf, New York's top backfield options are veteran Jonathan Stewart and second-year man Wayne Gallman.
The Giants will open their regular season Sept. 9 when they host the Jacksonville Jaguars.