Southern California is facing a second straight Sun Belt opponent after beating one by 49 points.
The next foe could be even easier to defeat since it will enter the Los Angeles Memorial Coliseum tied for the nation's second-longest road losing streak.
USC crushed Arkansas State 55-6 in last Saturday's opener. Cody Kessler passed for 236 yards and four touchdowns, Tre Madden rushed for 106 yards including a 65-yard score and the defense forced four turnovers in the Trojans' 18th straight season-opening win.
Now USC will get a chance to get Davis back on the field. He is the Trojans' top returning rusher, gaining 595 yards with four TDs a year ago before sitting out against the Red Wolves with a rib injury.
"He's physically cleared to play, now we've just got to get over the mental hurdle but I thought Justin practiced well (Tuesday)," coach Steve Sarkisian said.
Sarkisian also indicated that defensive lineman Claude Pelon could debut after undergoing knee surgery last month.
While Arkansas State went 7-6 last year and reached a fourth straight bowl game, Idaho went 1-10 in 2014 to cap a four-year stretch in which it had an FBS-worst 5-42 record.
The Vandals will bring in some people with notable family ties, starting with coach Paul Petrino - the younger brother of Louisville coach Bobby Petrino.
"I have a great deal of respect for Paul Petrino, he comes from a great lineage of coaches, his brother Bobby and what they've done in the past," Sarkisian said. "We know they're going to come in here fighting."
Quarterback Matt Linehan is the son of current Dallas Cowboys offensive coordinator and former St. Louis Rams coach Scott Linehan. Matt Linehan was sacked 40 times a year ago for the sixth-highest total in the FBS.
He completed 35 of 47 passes for 285 yards with one touchdown and two interceptions in last Thursday's season-opening 45-28 loss to Ohio.
The Vandals fell behind 21-0 in the first quarter, capped by an interception by Linehan that was returned 29 yards for a score. Linehan also lost a fumble on Idaho's opening drive.
"We were just beating ourselves early and had early turnovers and gave up big plays," Petrino said. "That's the stuff we have to stop. We can't do that and expect to beat good teams."
Linehan was sacked four times, one fewer than the number of times Kessler was dropped Saturday. That was a concern for Sarkisian along with the Trojans' 3-for-10 conversion rate on third downs.
"We pride ourselves on third down, being an excellent third-down team," Sarkisian said. "We weren't very good last week."
Linehan will face a defense that saw three freshmen linebackers make an impact last weekend. Cameron Smith became the first true freshman to start a USC opener at inside linebacker since 1978, Osa Masina ran back a fumble for a 46-yard touchdown and Porter Gustin flashed his skills as a pass rusher.
"I think we're all just feeding off each other and it's great to see these guys playing awesome," Smith said. "It's going to be a fun year."
The defense is seeking improvement after registering one sack in the opener.
USC has outscored Idaho 253-30 in going 8-0 in the all-time series, winning 38-10 in the last meeting in 2007.