SAN BERNARDINO — Entering fall camp, UCLA’s secondary was its most questionable unit, one that returned no starters and little experience.

Now the Bruins are down another man. Freshman cornerback Johnny Johnson, who separated his shoulder last week, will likely undergo surgery and redshirt the upcoming season.

Johnson was the first of four touted defensive backs to commit to UCLA’s 2013 class. Rated the 13th best cornerback in the country by Rivals.com, the 5-foot-10 Fresno native played well before injuring himself during one-on-one drills.

Head coach Jim Mora compared the injury to the one suffered by now-redshirt freshman Ishmael Adams, who played in the first two games of 2012 before sitting out.

“He’s a very good player but that’s just something that we’ll probably have to get taken care of,” Mora said of Johnson. “It’s disappointing but it gives someone else a chance to step up and play.

“I think Johnny’s disappointed but he’s going to be a great player here at UCLA. It’s just going to be delayed a little bit.”