USC is preparing for another dangerous quarterback in UCLA’s Josh Rosen

The quarterback deftly moves inside and outside the pocket, slipping tackles to deliver pinpoint passes.

He is capable of scrambling for long gains.

In terms of mobility, UCLA’s Josh Rosen is no Vernon Adams Jr., who last week dodged and darted out of the reach of USC players while passing for six touchdowns.

But Rosen has demonstrated poise and pocket presence along with an ability to throw accurately on the run. The freshman also showed speed two weeks ago on a 37-yard touchdown run against Washington State.

So USC’s defensive front has another challenge as the Trojans prepare for Saturday’s game against the Bruins at the Coliseum. The Pac-12 Conference South title and an opportunity to play Stanford for the conference championship Dec. 5 at Levi’s Stadium in Santa Clara are in play.

That prospect lessened the pain of Saturday’s 48-28 loss at Oregon.

“A South championship is still there,” linebacker Scott Felix said outside the locker room.

USC’s defense will try to make Rosen uncomfortable.

The former Bellflower St. John Bosco High standout has passed for 19 touchdowns, with seven interceptions. The Bruins, with a veteran offensive line, have given up only 12 sacks, fewest in the Pac-12.

USC sacked Adams three times, but the Trojans were left grasping at air on countless occasions.

“We just didn’t execute the way were supposed to, to eliminate the other things that happened in the back end,” defensive end Claude Pelon said.

Said Felix: “We missed a couple opportunities that ended up being big plays.”

USC has 33 sacks, 23 in the last six games.

The Trojans will need to pressure Rosen to take the onus off a secondary that looked confused against Oregon.

“We need to cover better, bottom line,” defensive backs coach Keith Heyward said after the game. “We’ve got to have our man and you’ve got to stick to him and you have to cover him.”

‘Rock’ of runners

Tailback Justin Davis carried the ball nine times and caught four passes in last season’s loss to UCLA.

The junior’s role is expected to increase after he rushed for a career-best 141 yards in 16 carries against Oregon and amassed 224 all-purpose yards.

“He’s been the rock in our [tailback] corps,” running backs coach Johnny Nansen said.

Davis caught three passes for 24 yards and returned two kickoffs for 59 yards, one for 36 yards.

“By far probably his best game of being a Trojan,” interim coach Clay Helton said.

Best(s) catch

Receiver Darreus Rogers struggled through a hamstring injury this season, but the junior looked sound against Oregon, especially when he made a leaping catch on a 27-yard touchdown play.

It was Rogers’ first touchdown this season.

Rogers, who had a season-best five catches for 53 yards against the Ducks, has caught 20 passes.

Steven Mitchell’s seven catches and De’Quan Hampton’s six receptions were career bests.

Gary.klein@latimes.com

Twitter: @latimesklein