Adam Hall stood on the Arizona Stadium sideline with a water-cooled brace around his injured right knee and embraced his new role: coach.

"We're going to play until they score," the UA safety bellowed.

The way things were going, the Arizona Wildcats could have played all day.

UA's defense stopped the offense on 14 of its 15 possessions and forced five turnovers during Saturday morning's scrimmage at Arizona Stadium. The Wildcats' defensive-minded approach in their first public workout of the spring was impressive, given the adversity they're facing.

Hall, the team's projected starter at free safety, tore the ACL in his right knee during Wednesday's practice and could be out for as long as seven months.

Defensive tackle Justin Washington and cornerback Shaquille Richardson were both held out of Saturday's scrimmage for precautionary reasons; Washington is recovering from shoulder surgery, and Richardson tweaked his shoulder in practice last week. Defensive tackle Sione Tuihalamaka was dealing with a family matter Saturday, and was not with the team.

Still, the defense shined. The Wildcats added five sacks and one tackle-for-loss; six different defensive backs broke up passes.

"I liked the energy we played with today," coach Mike Stoops said. "I think our overall group is going to be better … when it's all said and done, I think, defensively we'll be stronger than we've ever been."

For now, however, the unit is painfully thin.

Robert Golden moved from cornerback to safety to take Hall's spot. Josh Robbins, a former Canyon del Oro High School star, will back up Golden. Richardson and Jonathan McKnight will battle for a starting cornerback job opposite Trevin Wade.

Both Golden and Robbins admitted Saturday they have big shoes to fill. Many viewed Hall, a Palo Verde grad, as Arizona's top returning defender. He finished fifth on the team with 54 tackles and intercepted two passes as a sophomore in 2010.

"Adam was a big player for us; he came up and made some great plays," Golden said. "I know I have to step up and make the plays he was making."

Robbins, son of former UA standout cornerback Randy Robbins, said he's "still here learning everything, and trying to do as best I can." Robbins intercepted a pass Saturday, an impressive performance that could earn him more playing time in camp.

He credited Hall for the help.

"He's helping us get through everything, especially the blitzes and coverages," Robbins said. "It's a process. We gotta learn it."

Extra points

• Quarterback Nick Foles completed 16 of 29 passes for 141 yards Saturday, but he was intercepted twice. The offense's lone touchdown came when quarterback Bryson Beirne found Tyler Slavin for a 10-yard score on the final play. Beirne is wearing a new number - 7 - this spring. QB Matt Scott has switched from No. 4 to No. 10.

• Defensive end C.J. Parish looked strong at his new position: The former linebacker drilled running back Taimi Tutogi in the red zone, leading to a defensive stop.

• Two UA assistants have new roles. Garret Chachere will coach the running backs, while David Nichol will coach both inside and outside receivers. Chachere spent the last two seasons as the Wildcats' inside receivers coach.

Up next

• What: Arizona spring game

• When: Saturday, April 16, 1:30 p.m.