Marcus Lattimore surrendered on the spot. He took one look at his knee -- his wretched, distorted mess of a knee -- and kissed his NFL dreams goodbye.

"I just knew football was over with at that point," he said, "so I had to find something else to do with my life."

Spoiler alert: Lattimore didn't walk away after all. One of the greatest running backs in South Carolina history told his story from 49ers headquarters recently, not long after the latest strenuous workout of his comeback attempt.

The 49ers hope that the onetime supernova can be an impact draft pick in 2014, even if it's a full year after they selected him. The 49ers snagged Lattimore with a flier -- a fourth-round compensatory pick (131st overall) knowing from the get-go that he'd spend a year on the shelf.

Even now, the 5-foot-11, 221-pounder will be competing for a backup role with no guarantees. Lattimore, by his own assessment, is not all the way back, physically or mentally

But he's close enough to dream again.

"I'll probably be pouring out in tears, man, to tell you the truth," he said, when asked about the possibility of strapping on his helmet at Levi's Stadium. "I was just hoping to walk again."

The funny thing is, it didn't even hurt, at least not physically. On a second-and-10 from the 25-yard line, Lattimore took a handoff as one of the nation's best running back prospects. Two yards later, his career was in jeopardy.

One Tennessee defender hit him high, the other low, and it was as if someone put Lattimore's left knee in a blender. He wound up with an eye-chart of an injury: ACL, PCL, MCL -- all torn.

That play, the last of his college career, was Oct. 27, 2012, two days shy of Lattimore's 21th birthday.