COLUMBIA — For a few minutes, Archie Lattimore thought it was over. The years of sweating through practices, the hours in the weight room — all for naught now, as his son, Marcus, lay on his back down there on Williams-Brice Stadium’s grass.

It wasn’t supposed to happen like this.

Marcus had already shown enough talent as a South Carolina running back to cash in with the NFL. But what now? One helmet to the right knee during this Oct. 27 game against Tennessee, and nothing seemed for sure anymore, not even Marcus playing again. The sudden, awkward bend in his knee looked that catastrophic.

“Gut-wrenching,” is all Archie can still say about the moment.

Archie didn’t let the thoughts of finality linger. He rushed from the stands to the area just off the field where a cart transported Marcus. Archie stood there as the cart arrived. He hugged his son, who wept while the cart drove him off the field. Archie swallowed his own fears and told Marcus everything would be OK.

“He didn’t think so at the time,” Archie said. “He thought everything was over with.”

Marcus told his dad as much right there. Many who witnessed the injury at Williams-Brice or watched the gruesome replays on television probably thought the same thing.

Forty-six days later, on Wednesday afternoon, Archie sat in the bowels of Williams-Brice and watched his son declare for the NFL draft. He listened to USC team doctor Jeffrey Guy detail all the things that amazingly went in Lattimore’s favor with the injury, and why Lattimore should be able to play again. And Archie spoke with hope about the future.

“There’s nothing else to prove as a running back in college here,” Archie said.

Lattimore’s recovery period is 12 to 15 months post-surgery. He is progressing normally, Guy said, but won’t be ready work out at February’s NFL combine. He will attend to meet with teams. Their doctors will poke, prod and MRI his right knee and his left, which suffered an anterior cruciate ligament tear in 2011. He knows there are questions about his future, but he isn’t worried.

“I wouldn’t change anything that happened these past three years because it made me a better person, it made me a better man and it’s going to make me a better person in the future, knowing that I can get through anything,” he said. “I will get through this.”

The news broke Monday that Lattimore would turn pro. Given the small earning window for NFL running backs, it surprised no one. Archie said his son made the decision “a few weeks” ago.

“I 100 percent agree that Marcus should turn pro,” said USC coach Steve Spurrier. “At some point, when you can really play this game the way Marcus can, you need to be financially rewarded.”

To understand why Lattimore has that option now — and why, according to Guy, he might even be ready to play at the end of the 2013 NFL season — you must first consider the tiny part of the human body known as the peroneal nerve. This is the erve that provides sensation to the top of your foot and allows you to bend your ankle so that your foot and toes move slightly upward. It must work if you expect to make millions carrying a football.

Shortly after Lattimore was transported off the field, Guy began examining him at the stadium. Knee dislocations like the one Lattimore just suffered sometimes result in peroneal nerve damage, so the first thing Guy needed to do was make sure this nerve still worked in Lattimore’s right knee. He asked Lattimore to move his foot upward.

After all those practices and weight-lifting sessions and running past defenders, this simple exercise was, at this moment, the single most consequential physical feat Marcus Lattimore would ever accomplish at USC. Guy looked at Lattimore’s foot, knowing what the result of this test could mean for Lattimore’s promising future.

It moved.

“That’s a big deal,” Guy said Wednesday.

James Andrews, the renowned orthopedic surgeon and Guy’s mentor, called a few minutes later. He asked about the nerve. Guy delivered the good news. More positive tests followed. Lattimore had not damaged the bones, blood vessels or cartilage in his knee — all potential complications when you dislocate a knee and tear three of four ligaments, as Lattimore did.

By the time Guy, Andrews and Lyle Cain operated on Lattimore six days after the injury, they knew his prognosis was positive. During surgery, Lattimore required complete reconstruction of just one ligament, the anterior cruciate. Earlier this week, Lattimore got off crutches.

As he looked to the future Wednesday, he still remembered how he initially felt nothing when the helmet hit his knee, how he quickly “went into shock” and how his self-pity disappeared a couple days after the injury when teammate and friend Dylan Thompson visited him at home and told him, “Remember, God doesn’t make mistakes.”

At USC, they will remember Lattimore for how he helped change a football program. He ran for a school-record 38 touchdowns in just 29 career games. The Gamecocks, middling before his arrival in 2010, are 30-9 since.

The last time many people saw him at Williams-Brice, he rode away on that cart, incapacitated, a towel over his head. For a smaller audience Wednesday, he said his choked-up goodbyes, then led his family down a hallway, while accepting well-wishes. He stood tall in his black suit and walked out on his own.

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