Marcus Lattimore likely sitting out

San Francisco 49ers rookie running back Marcus Lattimore is not expected to play this season, sources told ESPN.

Within the next two weeks, San Francisco will have to decide whether to place Lattimore on injured reserve or the physically unable to perform list.

Regardless of which route the 49ers go, they have no plans to bring along Lattimore before he is fully recovered from the major knee surgery he had last year before being drafted in the fourth round with the 131st overall selection.

San Francisco still could decide to place Lattimore, who had hoped to play this season, on the physically unable to perform list, which would give him three weeks to practice with the team. But Lattimore likely will not see the field.

"I can't foresee him stepping on the field this season," one source told ESPN.