Los Angeles • This is a tale of a Utah defense that on Friday night against USC sagged early, then steadied, then sagged again, then soared, then sagged, then lost, 30-23.

At first, that D demonstrated bad intentions, when Leki Fotu hit Kedon Slovis on the Trojans’ second play, knocking him out of the game. Matt Fink replaced the freshman SC quarterback, and … well, he thrived, throwing for 351 yards and three touchdowns.

“We won a huge ballgame against a very good team,” USC coach Clay Helton said, afterward.

Over stretches, the very good defense wasn’t so very good.

Somehow, it held the Trojans to a mere 13 rushing yards, but, at the end, when the Ute offense needed the ball back, down a score, crucial yards on the ground were gained. Throughout, it could not rattle the sub QB.

The Trojans never went berserk on attack, gaining a total of 381 yards. The Utes got 457.

But the Utah defense could not come up big, and on two occasions, late in the game, it failed. First the Utes allowed a 69-yard scoring march, pushing the SC lead to 30-20. Then, after a Utah field goal, the Utes could not stop the Trojans’ offense as time ran out.

“Going into this game we expected them to pass, but towards the tail end they started to run and we just have to adjust," Utah linebacker Francis Bernard said. "Overall in the game, collectively as a defense, we just didn’t adjust well when we needed to and unfortunately that hurt us.”

USC showed its hand by throwing on its first seven plays, an opening drive that was punctuated by a 29-yard TD throw from Fink to Tyler Vaughns. That pass came against cornerback Jaylon Johnson, who some believe is the Utes’ best defensive player.

And like that, the Trojans were up, 7-zip.

It took the Utes all of a couple of minutes to tie it, with a varied 75-yard drive of their own.

Next, a 31-yard scoring pass from Fink to Amon Ra-St. Brown came when a Utah blitz stumbled and bumbled, failing to halt the quarterback. The count was 14-7 inside of the game’s initial seven minutes.

A series of mistakes killed the Utes’ immediate offensive response, which ended, fittingly enough, with a blocked field goal. The Trojans, too, settled down with a subsequent three-and-out. And the Utes, who next lost possession on downs, gained it back on an SC fumble. What transpired thereafter was a Utah drive that saw penalty flags hurt it and help it, everything from an unsportsmanlike conduct penalty on Kyle Whittingham to an unnecessary roughness flag on USC to a holding penalty on the Utes, among other indiscretions. Utah got a field goal out of it.

For a time, the Ute defense returned to its more recognizable form, pretty much snuffing the Trojans, causing their Air Raid to choke, bump and skid. And then, a 77-yard TD pass from Fink to Michael Pittman rearranged things.

“Mostly we just had no answer for their receiving core,” Whittingham said. “Michael Pittman did a number on us. We as coaches have to do a better job of coaching it and allowing our players to be more equipped to deal with a receiving core like that. We have to rethink some things coaching wise."

A subsequent interception by Terrell Burgess gave the Utes’ offense life, enabling it to score on a pass from Tyler Huntley to Cole Fotheringham with 3:47 left in the third quarter, making it 21-17, USC. A Utah field goal followed.

The Trojans got a safety, then a touchdown to go ahead by 10 midway through the fourth quarter. But after a Utah field goal, the defense could not get the ball back to its offense. USC retained possession over the final four minutes for the win.