ASU defensive tackle Will Sutton, expected to go high in the NFL draft, has only two sacks this year and is third on the team in tackles for loss (8.5). He and the Devils will try to put pressure on UCLA QB Brett Hundley.

Rick Scuteri / The Associated Press

At what point do college football boys become men?

Is it a certain number of games? A certain number of starts? Simply age? Hair on the chest? Baritone voices?

Arizona State and UCLA will find out Saturday afternoon at the Rose Bowl.

The Baby Bruins, still younger up front than some junior colleges, take on the wise old Sun Devils in a game that could end up determining the Pac-12 South.

UCLA will start three true freshmen — Caleb Benenoch, Scott Quessenberry and Alex Redmond — on the offensive line. Underclassmen litter the field.

Arizona State will counter with seven senior starters and two redshirt juniors on defense, and Will Sutton and Co. must be licking their collective chops.

“It’s not like they’re not talented; they’re just young,” Arizona State coach Todd Graham said of the UCLA offense Tuesday. “That’s where we have to dominate, up front.”

They’ve done so for almost six weeks now, having reeled off a five-game winning streak after a 37-34 loss to Notre Dame on Oct. 5, albeit against the Pac-12’s middleweights.

UCLA head coach Jim Mora knows his Bruins will have their hands full against such a veteran unit, particularly Sutton, who has commanded double teams for much of his senior season after returning as the conference’s player of the year.

“We all recognize what a talent Will Sutton is, but the other guys — I think they start eight seniors on defense — are good, too,” Mora said. “Their head coach is a defensive guy. It’s going to be a test all around for us on offense. This is certainly an enormous challenge.”

Last season, with a similarly young offensive unit, including then-redshirt freshman quarterback Brett Hundley, the Bruins passed the test. But just barely.

UCLA took a 35-26 lead on Hundley’s third touchdown pass, then watched as Arizona State stormed back to claim a temporary 43-42 advantage. Hundley responded with a game-winning drive, though, capped off by a Ka’imi Fairbairn 33-yard field goal to give the Bruins a 45-43 victory.

Both quarterbacks are a year wiser now, and a year better. Stanford coach David Shaw has had a front-row seat for both quarterbacks’ maturation, as his Cardinal defeated both teams by 14 points.

In a 42-28 loss to Stanford early in the season, Kelly had 367 yards and three touchdowns but also two interceptions. The Cardinal shut down Hundley even more on Oct. 19 in a 24-10 win, holding the redshirt sophomore to 192 passing yards with a touchdown and two interceptions.

“The combination quarterback is what gets you (at UCLA),” Shaw said. “You have to account for the running game and the passing game.

“Arizona State, I love the way their quarterback plays. The kid has moxie, as I like to say. He plays hard, he’s always in it. You can keep him down for as long as you can, but eventually he’s going to shake loose and make some plays.”

These are two horses rounding the corner, nearly neck-and-neck, one a stallion the other still a colt. They control their destinies — both teams are at 8-2, but Arizona State is 6-1 against Pac-12 foes, and UCLA is 5-2 — and finish off the season with big rivalry games.

But not before a battle of boys and men on Saturday.

“I address it, but they also understand the significance of this,” Mora said.

“We’ve talked about having to get into playoff mode after we lost to Oregon. I think they’ve been acutely aware of the significance each week.”

Added Graham: “We talk about it all the time. It’s something we’ve been talking about all year long. From the time we walked in the door year one, we talked about having one goal, winning a championship. Winning every day.”