Justin Davis’ injury could elevate Ronald Jones II to USC’s starting running back

Justin Davis was heard before he was seen after USC’s game Saturday afternoon. The clacking of crutches marked his emergence from the locker room. When he hobbled out, his right foot was in a black boot.

Davis hadn’t popped up from the turf immediately after a tackle in the second half of USC’s win over Colorado. Trainers attended to him, and he had a limp when they helped him off the field. Later, he was carted to the locker room with ice on his ankle.

USC Coach Clay Helton said the diagnosis was a high ankle sprain, an injury that could sideline a running back for multiple weeks.

On a teleconference with reporters on Sunday, Helton said he did not yet have a timetable for Davis’ return.

“Obviously a high ankle sprain to a running back is a hard thing,” Helton said. “I hope it gets better tonight. But usually with high ankle sprains, it takes a little bit.”

After taking just seven carries for two yards against Alabama, Davis, a senior, had enjoyed perhaps the best stretch of his career, starting with a 126-yard performance, in just 10 carries, against Utah. Against Arizona State, he rushed for 123 yards in 14 carries. He’d already rushed for 83 yards on Saturday before the injury in the third quarter.

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USC tight end Tyler Petite (82) scores the go-ahead touchdown against Colorado in the fourth quarter Saturday at the Coliseum.

  (Gina Ferazzi / Los Angeles Times)

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USC tight end Tyler Petite (82) is congratulated by wide receiver Darreus Rogers (1) after scoring the go-ahead touchdown against Colorado in the fourth quarter at the Coliseum on Oct. 8.  (Gina Ferazzi / Los Angeles Times)

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USC receiver Darreus Rogers (1) wrestles the ball away from Colorado’s Ahkello Witherspoon, turning a potential interception into a 46-yard reception to set up the Trojans’ go-ahead touchdown on Oct. 8.  (Gina Ferazzi / Los Angeles Times)

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USC receiver JuJu Smith-Schuster says he is not passing up the Rose Bowl game.  (Gina Ferazzi / Los Angeles Times)

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USC running back Ronald Jones II leans forward to try to pick up extra yards against Colorado defensive back Isaiah Oliver (26) in the second half.

  (Gina Ferazzi / Los Angeles Times)

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Trojans running back Ronald Jones II finds a hole to leap past Buffaloes defensive back Ryan Moeller in the second half.  (Gina Ferazzi / Los Angeles Times)

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USC can still win the Pac-12 South Division, thanks in part to a win over Colorado last month.  (Gina Ferazzi / Los Angeles Times)

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Trojans defensive end Porter Gustin (45) tries to deflect a pass from Buffaloes quarterback Steven Montez in the first half.  (Gina Ferazzi / Los Angeles Times)

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Trojans defensive back Adoree’ Jackson (2) celebrates with defensive tackle Rasheem Green after intercepting a pass against the Buffaloes.

  (Gina Ferazzi / Los Angeles Times)

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USC running back Justin Davis (22) breaks through an attempted tackle by Colorado defensive back Chidobe Awuzie.

  (Gina Ferazzi / Los Angeles Times)

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Running a quarterback keeper, USC’s Sam Darnold (14) stretches as he is brought down by Colorado defensive end Jordan Carrell in the first half Saturday.  (Gina Ferazzi / Los Angeles Times)

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Trojans Coach Clay Helton signals a first down in the first half against Colorado on Saturday.  (Gina Ferazzi / Los Angeles Times)

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Trojans tight end Tyler Petite (82) leaps into the end zone to score after a pass from quarterback Sam Darnold in the second quarter.  (Gina Ferazzi / Los Angeles Times)

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USC running back Ronald Jones II dives for extra yards against Colorado during the first half.

  (Gina Ferazzi / Los Angeles Times)

The injury could damage his pursuit of his first 1,000-yard season. He finished 98 yards shy of the mark last season. He is on pace for 934 yards in the regular season.

Davis’ patience and hard running, and his improved ability to break off longer runs, had reignited USC’s running game as USC’s other option, Ronald Jones II, struggled to get started.

In Davis’ absence, Jones said he’d begun to find the rhythm that had eluded him this season. He rushed 10 times for 56 yards against Colorado and caught a screen pass on third down to move the chains — a promising sign, as he has been skittish, at times, in the passing game early in his career.

“When you get those back-to-back carries and a rhythm, you definitely get a better feel for the game,” Jones said.

If Davis is unable to play, Aca’Cedric Ware would likely become Jones’ the backup, with Dominic Davis working into the rotation.

A 2012 study, by researchers at the University of Michigan, of 20 players who suffered high ankle sprains found recovery time from the injury could vary widely, from two days to 30 days. On average, it took two weeks to return to the field.

“If Justin can’t go, I know those guys will pick up the slack,” Helton said. “It’s next man up.”

Fumbles fester

A day after USC’s win, Helton mused that, “the good lord was watching over us yesterday.”

It was a reference to USC’s turnovers — all four of them — that, Helton said, are usually enough to lose a game.

Three of the four were credited to quarterback Sam Darnold, who has mostly avoided having passes intercepted but has had a troubling tendency to fumble.

Helton said ball security would be a point of emphasis in practice. He said he would stress two major points to Darnold.

First, he said, Darnold can’t let the ball separate from his body, even if he is stretching at the goal line. That cost USC a touchdown early in the game against Colorado.

Helton said he has already underlined his second point.

“Sliding’s not a bad thing,” Helton said. “Did that later in the game. Needs to do it more.”

Quick hits

Linebacker Michael Hutchings sustained a subluxation of his shoulder — effectively a partially separated shoulder. Hutchings will undergo an MRI exam, “but we feel like he can be back for this week,” Helton said. … Right tackle Zach Banner (ankle sprain) did not play Saturday for the second straight game. “Hopefully he’ll be back this week,” Helton said. … Tight end Taylor McNamara (back strain) tried to warm up before Saturday’s game but experienced discomfort and did not play. ... Linebacker John Houston Jr. sustained a minor knee injury. … Safety Jonathan Lockett re-injured his sprained shoulder. ... Jabari Ruffin (concussion protocol) remains out.

zach.helfand@latimes.com

Follow Zach Helfand on Twitter @zhelfand