LOS ANGELES— Freshman Josh Rosen will be No. 13 UCLA's starting quarterback in the season opener against Virginia.

Bruins coach Jim Mora made the announcement Wednesday ahead of the Sept. 5 opener for the team.

Rosen was the consensus top quarterback recruit in the 2015 recruiting cycle, and he enrolled at UCLA last winter. Nearly three weeks into training camp, he formally won the job over redshirt juniors Jerry Neuheisel and Mike Fafaul.

"At the end, it came down to Josh and Jerry," Mora said. "When you have done it as long as we have done it, at some point it just becomes apparent to you. You get a gut feeling. You have seen enough and you say, 'You know what? It's time to make that decision, and let's go.' And that's what we did."

When UCLA broke camp at Cal State San Bernardino last weekend, a decision regarding Brett Hundley's successor did not appear to be coming anytime soon.

Mora had said he was still waiting on someone to claim the job, and that was before launching into an end-of-practice diatribe against Rosen last week in which the fourth-year coach pointedly told reporters, "You can tell all your readers this is why there's no starter named."

But Mora said the 18-year-old Rosen's emotional stability and steady improvement against the Bruins' ferocious defense were key factors in the decision. Rosen will be able to rely on that defense, an experienced offensive line, the Pac-12's leading rusher last season in running back Paul Perkins, and a talented collection of tall receivers.

Yet Mora cautioned that any first-year player will make mistakes, even one as talented and acclaimed as Rosen.

"There are going to be some plays that are frustrating, there are going to be some plays that are dumbfounding, but there are also going to be some great plays," Mora said. "We are going to see him develop through the year."

Rosen starred at Bellflower [Calif.] St. John Bosco, passing for 8,473 yards and 90 touchdowns in his high school career.

Rosen faces a significant task in replacing Hundley, a three-year starter who set the UCLA record for career yards passing and went 3-0 against rival Southern California before leaving early for the NFL.

Rosen was told of the decision Wednesday morning, asking to call his parents and share the news with them, Mora said. After meeting with each of the three contenders, Mora did not make a formal announcement to the rest of the team, saying he wouldn't do it when making "a switch at left guard or nose tackle or inside linebacker or corner."

The only feedback Mora said he received during practice was from senior wide receiver Jordan Payton.

"I said, 'Did you know I talked to the quarterbacks?'" Mora said. "He said, 'Yeah,' and that was the extent of it."

Mora praised the character and leadership of Neuheisel, the son of former UCLA quarterback and coach Rick Neuheisel, but ruled out any sort of time-sharing arrangement.

"I've made it very, very clear that I am a one-quarterback type of coach," Mora said. "I want to put a guy in that position and support the heck out of him and help him have success and rally around him if he's struggling. That's what I will do, that's what this staff will do, and that's what this team will do."