BOULDER, Colo. -- A year ago, 12 penalties and four turnovers would have doomed the Colorado Buffaloes.

Not this year. Instead of folding, Colorado is overcoming mistakes and pulling out victories.

Sefo Liufau shook off a first-half injury to lead Colorado to two scoring drives in the second half, Isaiah Oliver returned a punt 68 yards for a clinching touchdown, and the No. 21 Buffaloes beat the UCLA Bruins 20-10 Thursday night to keep their Pac-12 title hopes alive.

Running back Phillip Lindsay had 11 receptions, 149 total yards and a touchdown for the Buffaloes (7-2, 5-1), who sits atop the Pac-12 South Division and are bowl-eligible for the first time in nine years.

Colorado won its third straight despite a mistake-filled game. The Buffaloes were called for 12 penalties for 128 yards, including eight personal fouls, and committed four turnovers.

"The bye week helped us all heal, we practiced, we kept the tempo, but we played sloppy," said Lindsay, who set a program record for catches by a running back in a single game. "If we want to be Pac-12 champions, then we've got to execute. Defense is bailing us out. That will only take us so far."

UCLA had 13 penalties for 96 yards -- including two personal fouls -- and missed three field goals, including one that was blocked.

"It was chippy, we just have to keep our composure and not let that affect us in the game," Bruins linebacker Jayon Brown said.

Liufau finished 19 of 30 for 143 yards with two interceptions. He also ran for 58 yards despite missing the last 5:43 of the first half after he was sacked by UCLA defensive lineman Takkarist McKinley. Liufau fumbled and was knocked out of the game for two series. Backup Steven Montez came on and threw an interception.

Liufau returned at the start of the second half and led Colorado to a pair of field goals.

"I thought Sefo was out. He took a shot," Montez said. "He's a warrior. He takes a hit, gets up and just brushes it off. I know he's hurting and he doesn't let anybody see it."

Mike Fafaul was 15 of 29 for 185 yards and one touchdown, and Darren Andrews had six catches for 88 yards and a score for UCLA (3-6, 1-5).

Fafaul took over for starter Josh Rosen, who was ruled out for the rest of the season due to a shoulder injury.

"I found out a couple of days ago that he was having surgery," Fafaul said. "It's tough for him. He's getting ready for surgery next week."

The Bruins have lost four in a row by a total of 26 points. The Colorado game marked the first time they fell by more than a touchdown.

"It's incredibly disappointing. We had so many opportunities with four takeaways in the first half," UCLA coach Jim Mora said. "It's terribly disappointing not being able to find points. Terribly disappointing."

The Buffaloes trailed 10-7 at halftime, but Oliver's 42-yard punt return led to Chris Graham's 21-yard tying field goal.

Colorado took a 13-10 lead on another Graham field goal, this one from 37 yards out early in the fourth quarter.

Oliver sealed it with his punt return with 5:27 left, and the Buffaloes' defense stopped the Bruins after they drove to the Colorado 19.

"Our defense certainly picked up a lot of the slack," Colorado receiver Bryce Bobo said. "The defense was straight lockdown."

Colorado went ahead 7-0 on Lindsay's 1-yard plunge with 5:49 left in the first quarter. Linebacker Kenneth Olugbode's interception and return into UCLA territory set up the score.

The Bruins wasted no time in getting even. After a long runback on the ensuing kickoff and the Buffaloes' third personal foul gave UCLA the ball in Colorado territory, Fafaul hit a wide-open Andrews for a 39-yard touchdown with 4:04 left in the first.

Liufau's second interception of the first half gave UCLA the ball at Colorado's 28, but the Buffalo defense stiffened. The Bruins lost 3 yards and settled for JJ Molson's 48-yard field goal to go up 10-7.

UCLA got the ball back when McKinley's sack of Liufau caused a fumble, and Brown returned it to the Buffaloes 18-yard line. However. Colorado's Chidobe Awuzie blocked Molson's 26-yard attempt to keep it a three-point game.

NOTES: Colorado DL Jimmie Gilbert was ejected for targeting early in the first quarter. ... UCLA is 12-7 in the month of November since 2012. ... Colorado QB Sefo Liufau's interception in the first quarter was his first in 152 pass attempts, the longest stretch without throwing one in Colorado program history. ... The Bruins' defense ranks seventh nationally in pass-efficiency defense.