Clay Helton’s chances for USC coaching job build with each win, but he’s not saying that

A day after his team overcame a sluggish start to win its third game in a row, USC interim Coach Clay Helton was still marveling.

The Trojans trailed Arizona by 14 points — “We were just sloppy in the first quarter. I don’t how else to put it,” Helton said Sunday — before coming back for a 38-30 victory that included 472 yards of offense.

“I just appreciate being at a place where that’s a bad day at the office,” Helton said, laughing, during a teleconference with reporters.

Last month, when he was named as the fired Steve Sarkisian’s replacement, Helton said he wanted the permanent position. But he has since strategically deflected questions about whether his chances might be growing with each succeeding victory.

USC is 6-3 overall and 4-2 in Pac-12 Conference play heading into Friday night’s game against Colorado. Momentum is building for Helton, who could make a strong case for himself if he can engineer victories over the Buffaloes, Oregon and UCLA.

Helton said he has followed advice given to him by his father, Kim, a former college and NFL coach, and also Sarkisian.

“Be yourself,” Helton said he was told, “and that’s what I’m doing.”

Helton was a longtime assistant at Memphis and has been on USC’s staff for six seasons.

Since taking over as interim coach — he also served in that role for the 2013 Las Vegas Bowl — Helton said he has placed trust in offensive assistants for game-planning and in-game adjustments.

“These guys I trust with my livelihood wholeheartedly,” Helton said, “and obviously it’s paying off for us right now and I know it will continue.”

He also said he “loved” the adjustments defensive coordinator Justin Wilcox made Saturday night.

“Justin has had the opportunity to make corrections throughout the season and will continue to do that,” Helton said.

Plattenburg steps up

Sophomore safety John Plattenburg was sidelined against Utah and played only on special teams against California.

So he was eager to play on defense against Arizona before a homecoming crowd at the Coliseum.

“Just giving the folks a good show,” he said.

Plattenburg’s second-quarter interception set up Cody Kessler’s touchdown pass to JuJu Smith-Schuster.

After tailback Ronald Jones II scored on a long run to give USC a 31-23 lead, Plattenburg saved a touchdown by chasing down Arizona kick returner Tyrell Johnson.

Helton said the play would be shown to the team Monday.

“We always show very uncommon effort and that was one of the plays that I thought was huge in the game,” Helton said.

Pelon pushes through

Defensive end Claude Pelon, who made several key plays in last season’s victory over Arizona, made a game-turning play Saturday night.

Pelon, back from a knee injury that sidelined him for three games, stopped running back Orlando Bradford on a fourth-and-two play at midfield in the third quarter.

“I kind of felt they were going to go for it and give it to him,” Pelon said. “I was just at the right place at the right time.”

USC, trailing 20-17 at the time, went on a 21-3 run after the stop.

“Might as well have been a turnover for us,” Helton said. “It created a huge momentum swing.”

Quick hits

Linebacker Cameron Smith suffered a right shoulder injury and will have an MRI exam Monday, Helton said. . . . Linebacker Su’a Cravens had eight tackles, including 2½ for losses, despite playing with a lacerated finger that required stitches during the game. . . . Safety Leon McQuay III was held out of the game because of a knee strain he suffered last week in practice. . . . The Trojans usually do not practice on Mondays, but they will this week because they play on Friday.

gary.klein@latimes.com

Twitter: @latimesklein

Times staff writer David Wharton contributed to this report.