Late in the penultimate practice of Southern California's regular season on the beguilingly sunny Wednesday before Thanksgiving, Leonard Williams picked up a walk-on tailback and body-slammed him to the turf.

"He only knows one way to play the game," USC coach Steve Sarkisian said.

Williams' rude treatment of James Toland IV in an otherwise mellow workout is just another example of the defensive lineman's spectacular combination of talent and work ethic. The junior known as Big Cat might be the nation's best player in the trenches, but he still craves daily competition and improvement for as long as he's at USC.

Williams won't claim ignorance of his NFL draft status like his former teammate, Marqise Lee. He realizes he could be the top pick next year, but Williams insists he's firmly focused on the Trojans (7-4), who finish their regular season at the Coliseum against intersectional archrival Notre Dame (7-4) on Saturday before a bowl trip.

"I'm just going to choose at the end of this season, after the bowl game," Williams said of his pro fate. "Of course I've thought about it. I've been hearing about it all season."

More like three seasons.

Although a run-stopping, two-gap-clogging, double-team-drawing defensive lineman rarely racks up gaudy statistics, Williams has been a rock in the middle of USC's line for his entire tenure in downtown Los Angeles. He has 8 1/2 tackles for loss, six sacks and three forced fumbles this season despite battling multiple blockers and pass-happy Pac-12 offenses going anywhere except his arm's reach.

From Daytona Beach, Florida, Williams loves his West Coast school, and he embraces college football's traditions. He has been anticipating the Trojans' two biggest rivalry games all year, eager for the chance to beat UCLA and Notre Dame for the first — and perhaps only — time in his career.

Although he gets his third chance against Notre Dame on Saturday, Williams was crushed when the Bruins beat USC last week.

"I love SC, and I still haven't got to beat UCLA," Williams said. "That would be bad to leave without beating them. I'm a part of SC tradition. I'm a Trojan, and just being a Trojan and being able to say you never beat them is something that I would regret for the rest of my life."

Williams is probably the only person who thinks there's even a slim chance he won't leave USC for NFL millions after the season. He's a delectable pro prospect often compared to Richard Seymour, and the strong chance to be a top-five pick is likely too lucrative to pass up.

Yet he still has a deep bond with Ed Orgeron, the former USC defensive assistant who persuaded Williams to follow him across the continent to Hollywood. Williams was stunned and hurt when Orgeron left USC last December after the school chose Sarkisian for the permanent job, and he stays in contact with Orgeron, who has expressed interest in returning to the Trojans next year.

But Williams seems pleased with Sarkisian's staff as well, and the new coach was overjoyed to inherit a talent of Williams' magnitude.

"In this day and age of guys reading their names in every potential mock draft and where they're supposed to go, and All-American status, we see so many guys maybe not go as hard all the time, maybe take themselves out and whatnot," Sarkisian said. "Leonard Williams has not done that once this year, and he has not been 100 percent healthy. He comes out. He works hard. He plays his tail off. We're thankful for that."

Unless Williams goes against all conventional wisdom and joins quarterback Cody Kessler in returning for his final season of eligibility, Saturday will be his Coliseum farewell. Williams' defensive teammates praise his leadership and steadiness in another trying season for the Trojans, who have known nothing but upheaval in his three years on campus.

"We have sanctions. We don't have as many scholarships. We've been dealing with coaching changes since I've been here," Williams said. "We have a fresh staff this year, but there's a lot of injured players. There's a lot mentally that we've got to deal with. We've just got to make sure we're mentally strong enough to go in there against Notre Dame."