Colorado controls its destiny in the Pac-12 South Division.

After Utah lost to Washington while the Buffaloes enjoyed a bye week, 21st-ranked Colorado (6-2, 4-1) is alone in first place in the South heading into Thursday night's home game against UCLA, starting at 9 p.m. ET.

UCLA (3-5, 1-4) was the preseason pick of the league's media to win the division, but the Bruins have struggled in the run game and likely will be without starting quarterback Josh Rosen for a third consecutive game because of a nerve problem in his throwing shoulder.

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With a win, the surprising Buffaloes will match their conference victory total from their first five seasons in the league combined.

Colorado already has accomplished one goal by qualifying for a bowl game for the first time since 2007, but bigger prizes are within reach.

"They've got everything in front of them they've always dreamed of, and they've worked so hard to get here, they don't take it for granted," said Colorado coach Mike MacIntyre. "It's not like it's a common occurrence. ... These guys will stay on each other, which is awesome."

Colorado, which is coming off a 10-5 victory over Stanford on Oct. 22, has three of its final four games at home. Utah and USC, both 4-2 in the conference, are the only realistic challengers to the Buffaloes. Every other team in the South has at least four league losses.

Colorado has great balance. Senior quarterback Sefo Liufau directs an offense that is 19th nationally with 495.8 yards per game. The running game has been strong; the Buffs have rushed for 247, 260, 260, 263, 315 and 224 yards in their six victories, while being held to 64 and 96 in their two losses.

The Buffs defense is 12th nationally, allowing 307.8 yards per game.

UCLA, meanwhile, is trying to find balance after basically abandoning the run game in its most recent game, a 52-45 loss to Utah. The Bruins' running backs carried just 10 times while quarterback Mike Fafaul attempted 70 passes.

"We're always grinding," said offensive coordinator Kennedy Polamalu.

"We've simplified the task, and I really believe with the young men we have all the way around -- from the linemen, tight ends, receivers and the runners -- we're getting better. I really want balance to help our quarterback."

It's not like UCLA doesn't have talent at running back.

Sophomore Soso Jamabo was arguably the top running back prospect in the 2015 class. Nate Starks was a four-star recruit. Bolu Olorunfunmi has done some nice things.

But Jamabo and Starks have each been slowed by injuries a various times, including against Utah. UCLA's top three running backs have rarely been available/healthy at the same time this season.

The Bruins are last nationally in rushing at 85.5 yards per game.

Still, UCLA hasn't been far off this season, losing its five games by a combined 32 points.

"We haven't won, but we haven't been blown out," said Bruins coach Jim Mora. "Our guys fight. They are a bunch of fighters. I really respect that about them."

Fafaul, a fifth-year senior and former walk-on, completed 40 of 70 passes for 464 yards, with five touchdowns and four interceptions, in the loss to Utah on Oct. 22. His focus in practice has been efficiency -- not forcing anything. Fafaul has thrown eight interceptions in 122 pass attempts.

Colorado ranks second in the Pac-12 with 11 interceptions. Cornerback Tedrick Thompson has four of them. The other corner, Chidobe Awuzie, is a potential mid-round draft pick, according to NFLDraftScout.com.

The Buffaloes have held two of five conference foes without a touchdown this season.

Liufau, who missed three starts this season because of an ankle injury, has taken every snap in the past two games. He is riding a school-record streak of 148 consecutive passes without an interception.

Colorado running back Phillip Lindsay is third in the conference with 93.1 rushing yards per game. He has rushed for 350 yards in his past two outings.

"To be able to just watch our running backs break big runs, I know I don't have to do as much," Liufau said. "I don't have to go out there and think that I have to make play after play after play just to keep us in a game."

UCLA's run defense has been good at times this season, but the Bruins allowed Utah's Joe Williams to run wild for 332 yards.

The Bruins have won all five meetings with Colorado in conference play, but the past two were decided by four and three points.

"I think they have been making steady progress with Coach Mac," Mora said. "The last two years, they have been great games. We kind of squeaked them out."