• Quarterback Ty Dieffenbach, making his first UCLA start following Nico Iamaleava’s injury, passes for 264 yards and the No. 12 Bruins beat Wisconsin 17-7 to remain the only unbeaten team in the Big Ten.

Behind a standout performance from quarterback Ty Dieffenbach in his first UCLA start, the No. 12 Bruins defeated Wisconsin 17-7 at the Rose Bowl on Saturday.

Dieffenbach orchestrated a six-play, 89-yard drive in the fourth quarter to help seal the win for the Bruins, who clinched bowl eligibility by improving to 6-0 under coach Bob Chesney. UCLA is the only undefeated team in the Big Ten.

Although UCLA (6-0, 4-0) entered with one of the most potent ground attacks in the nation, the Badgers’ (4-2, 2-1) stalwart defense — a unit that ranked No. 15 in total defense and ninth in passing yards allowed heading into the game — held UCLA to just 3.2 yards per carry. Heisman Trophy contender Wayne Knight was limited to just 29 all-purpose yards, though he scored his 12th touchdown of the season.

With UCLA struggling to get a push at the point of attack and the Wisconsin defense sealing the edge, the Bruins put their trust in Dieffenbach, who started in his first Football Bowl Subdivision game in the wake of Nico Iamaleava’s season-ending injury last week against Oregon.

The understudy shined in the spotlight.

Even though expectations were tempered for Dieffenbach, he largely did not miss a beat, completing 22 of 33 passes for 264 yards — better than any single-game passing yards total Iamaleava has produced at UCLA.

Dieffenbach set up UCLA’s first touchdown in the second quarter when he completed a 21-yard pass to Jalen Saint Paul one play before Wayne Knight scored on a one-yard carry.

UCLA’s second score — a touchdown that put the Bruins up 10 points in the fourth quarter — capped Dieffenbach’s most impressive drive. Starting at the UCLA 11, Dieffenbach connected on passes of 28 and 33 yards on a drive that culminated with Anthony Woods scoring on a three-yard run.

Dieffenbach looked poised in the pocket as he made passes under pressure. He excelled on third down, with UCLA converting on 13 of 20 tries. He threw one interception, which came on a Hail Mary as expired in the second quarter, and took just one sack.

Giving Dieffenbach some breathing room, UCLA’s defense dominated again, holding Wisconsin to 214 total yards. Even without UCLA starting outside cornerback Rodrick Pleasant, the Bruins’ secondary blanketed the Badgers in coverage, giving up just 66 passing yards, with Wisconsin’s top receiver Jaylon Domingeaux finishing with 26 yards.

And while the “Bruin Bullies” held up at the line of scrimmage against the Badgers’ tailbacks, Wisconsin quarterback Colton Joseph ran for 71 yards and one touchdown, using various formations and fakes to confuse the Bruins’ stacked box.

While UCLA failed to produce a takeaway for the first time this season — despite forcing two fumbles, both of which were recovered by Wisconsin — the Bruins made several key stops to help UCLA stay in control.

A 10-yard sack from fifth-year linebacker Jalen Woods on third down late in the second quarter led to an unsuccessful 46-yard field-goal attempt by Gavin Lahm, leaving Wisconsin scoreless at halftime.

After Wisconsin scored its only touchdown and subsequently forced UCLA into a three-and-out late in the third quarter, the Badgers had the ball with a chance to take the lead. But the Bruins forced two incomplete passes and stuffed Joseph at the line to force a punt.

In the fourth quarter, UCLA stopped running back Darrion Dupree short of a first down on fourth-and-two at the Bruins’ 48 to all but end the Badgers’ hopes of a comeback.