Coach Steve Spurrier said the injury is something Lattimore can come back from to play football again.
There were no fractures or additional injuries, according to team physician Jeffrey Guy.
Spurrier visited Lattimore on Sunday and said the junior had a good attitude about his condition. Spurrier said Guy was able to put Lattimore's knee back in place soon after he was taken from the field to the hospital.
Spurrier said the injury was significant, but discounted speculation Lattimore never would play football again. Lattimore has not used a redshirt season so he could take as long as necessary to recover and still return to the Gamecocks for the 2014 season.
"We're optimistic his football days are ahead of him," Spurrier said.
Lattimore is resting comfortably and will be evaluated over the week, according to the school.
Spurrier hasn't yet talked with Lattimore, who turns 21 on Monday, about his future. Spurrier said recovery will take some time, perhaps more than one offseason.
"He knows what the road ahead is," said Spurrier, who visited Lattimore Sunday. "We're all hoping and praying he'll be back."
That didn't seem possible to anyone who watched Lattimore fall or saw the slow-motion replays of the second-quarter hit. Lattimore was wrapped up from behind on a 2-yard run when Vols defensive back Eric Gordon came in low. Lattimore's right leg sickeningly flopped over and slammed against the turf.
Trainers immediately surrounded Lattimore. Eventually, players from both sides came out to comfort Lattimore and surrounded him as he was lifted into a cart and taken away by ambulance.
"I saw the look in his eyes when he was on the ground," South Carolina receiver Ace Sanders said. "He was really heartbroken about the injury. We were just trying to keep him strong."
A host of sports figures and other celebrities sent Lattimore support via Twitter, including New York Jets quarterback Tim Tebow, Notre Dame linebacker Manti Te'o, and Hootie and the Blowfish singer and South Carolina alum Darius Rucker.
Spurrier said he's gotten so many messages of support, he believes Lattimore may be the most popular player in South Carolina history.
Gamecocks quarterback Connor Shaw said the team played for Lattimore in the second half. South Carolina (7-2, 5-2 Southeastern Conference) held on for a 38-35 win over Tennessee (3-5, 0-5). The Gamecocks moved up six spots to No. 11 in the latest AP rankings. They don't play again until Nov. 10 against Arkansas.
The Gamecocks had to play without Lattimore the second half of last season, too, after he tore ligaments in his left knee against Mississippi State. South Carolina went 5-1 with its star rusher on the sidelines, an experience Spurrier hopes the team can draw on down the stretch this year.
"We'd rather have Marcus on our team, that's for dang sure," Spurrier said. "In life, sometimes you've got to move on with whatever hand you're dealt."
Lattimore is expected to be re-evaluated this week. He's already made it back once through the gut-wrenching rehab process, returning as one of the SEC's top backs this season. He finishes this year with 662 yards and 10 touchdowns. Lattimore scored on a 28-yard run against Tennessee, adding to his school record of 41 career TDs.
Vols receiver Justin Hunter said Tennessee players wanted to show their respect for Lattimore.
"We felt for him. We knew he came off a knee injury and for this to happen to him is bad," Hunter said. "The whole team just wanted to go out and show support."
Whatever decisions Lattimore makes about his future, he's got Spurrier's blessing.
"We'll just go a day at a time and allow the doctors and Marcus and a lot of prayers do their work," Spurrier said.
Information from The Associated Press was used in this report.