USC claims Pac-12 title with 31-28 defeat of Stanford

In the shadow of its goal line, with the Pac-12 championship game and the success of the season in the balance, USC’s defense faced a goal-line stand of unusual length: six plays.

In six plays, Stanford had the opportunity in the fourth quarter Friday evening to steal control of the game that USC otherwise dominated.

In six plays, there was questionable decision-making that gave Stanford new downs. There were brief flashes of physical football. And a game-saving, rabbit-out-of-the-hat play.

It was six plays in this 31-28 USC victory. It was also the story of USC’s season.

USC was clinging to a three-point lead when fourth down finally arrived, from the one-yard line at Levi’s Stadium. Stanford coach David Shaw called for a run to the left. On the backside, outside linebacker Uchenna Nwosu saw the linemen tighten their splits. He knew it would be an inside run, one of Stanford’s favorites. The play called for Stanford to leave Nwosu unblocked. That was by design. The design was flawed.

Nwosu tore around the line and lassoed Cameron Scarlett by the ankles.

On the ensuing drive, USC marched down the field, scored a touchdown for a needed cushion and, for the first time since 2008, the Trojans became the conference champions.

“Man, just they found a way,” USC coach Clay Helton said.

He might have said the same after most games this season. The six-play stand both erased and captured a season of frustration, close wins and occasional brilliance. USC can put aside angst about inconsistency. It no longer needs to defend its record. USC is 11-2. It defeated its North Division boogeyman twice in the same season.

The three-point win probably lacked the panache that USC needed to make an unprecedented leap from No. 10 in the College Football Playoff rankings and into the top four. The Trojans have guaranteed themselves a New Year’s Six bowl. USC players said, if they do not make the playoff, they have at least made a statement.

In the week before the game, USC safety Chris Hawkins said he saw a wave of fan complaints.

“They should be on their knees praying, begging for forgiveness for what they were saying,” Hawkins said after the game.

Tight end Tyler Petite said the title showed that “SC’s no joke anymore.”

“Yeah, I would say we’re back,” Nwosu said. “We won the Rose Bowl last year, the Pac-12 championship this year. We’re starting to build and starting to keep the chain moving.”

The Trojans controlled the game and never trailed. They outgained Stanford 501 yards to 343.

USC limited Stanford’s Heisman Trophy candidate running back, Bryce Love, who was limited by an ankle injury, to a mortal 125 yards.

Ronald Jones II took a career-high 30 carries for 140 yards and two scores. Quarterback Sam Darnold threw for 325 yards and two touchdowns. Michael Pitt-man Jr. set a Pac-12 title-game record with 146 yards receiving.

The only thing USC failed to do was shake Stanford.

Pittman and Tyler Vaughns scored touchdowns in the first half, but with the clock winding down, Stanford’s K.J. Costello squeezed a pass between two USC defenders to JJ Arcega-Whiteside for 42 yards. It set up a touchdown run by Scarlett with seconds left in the half. Instead of a two-score advantage, USC led only 17-14.

The teams traded scores in the third. Then, in the fourth quarter, a short punt and Costello gave Stanford its chance. He escaped on a play-action bootleg to reach USC’s three-yard line.

A delay of game forced Stanford back on first down. Then the stand began. First play: USC blew up a run to push the Cardinal to the 11. Second play: Costello threw the ball away … but a late hit by John Houston Jr. gave Stanford new downs and new life.

Stanford punched the ball to the two-yard line by third down, then the one-yard line by fourth.

Shaw could have elected to kick the chip-shot field goal to tie the score. Instead, he kept Stanford’s vaunted jumbo package on the field. “You’re talking about one of the best short yardage run teams there is in the world,” Helton said.

Nwosu sent it off.

Two plays later, while narrowly escaping a sack in the end zone, Darnold hit Pittman for 54 yards, then 12 more on the next play. Jones punched in an eight-yard score.

“We live in a high-pressure world of great expectations on the brightest stage, brightest lights, only game on in the world tonight,” Helton said. “These kids stood up on the goal line stand and decided to go 99 yards to finish the game. That defines who they are.”

But the game wasn’t sealed yet. Costello hit Haden Smith for a touchdown to make it 31-28. With about 30 seconds left, USC failed to convert a third down. The Trojans could’ve given Stanford a shot to tie. Instead, offensive coordinator Tee Martin called a play-action pass to freshman tight end Josh Falo and Darnold found him for the first down.

Helton said he didn’t consider punting. He said he thought it was time for USC to win the championship.

zach.helfand@latimes.com

Follow Zach Helfand on Twitter @zhelfand