BOULDER, Colo -- Colorado completed an improbable journey from worst to first. The final step forward came with a big assist from the Buffaloes' defense.

Colorado vexed Utah's offense for four quarters, forcing four turnovers and repeatedly holding the Utes to field goals in the red zone to scratch out a 27-22 victory on Saturday night. It helped the Buffaloes snap a four-game losing streak to Utah, reach 10 wins in a season for the first time since 2001, and clinch the school's first Pac-12 South title.

Now Colorado (10-2, 8-1 Pac-12 South) will face Washington in the Pac-12 Championship Game on Friday with a shot at its first outright Pac-12 crown. It marks an incredible turnaround for a program that won just five total conference games during its first five seasons in the league -- which included winless Pac-12 seasons in 2012 and 2014.

"It's a great feeling to put in all this hard work with these guys and to finally get something out of it," senior quarterback Sefo Liufau said. "We've been working really hard for all the time I've been here and we don't have much to show for it. But this year we do. I can't thank the defense enough. Those guys are stepping up this year and making plays."

Liufau threw for 270 yards and a touchdown to lead the Buffaloes on offense. Colorado struggled to move the ball at times against Utah's defense, but the Buffaloes did enough to hold down the Ute offense to stay a step ahead all night.

Troy Williams threw for just 160 yards, a touchdown and a pair of interceptions for Utah while Joe Williams added 97 yards on 26 carries. The Utes (8-4, 5-4 Pac-12) could not overcome an inability to hold onto the ball or finish drives in Colorado territory.

"It's not the way we wanted to go out," Troy Williams said.

Utah had chances to go ahead in the third quarter, but could not get any production in the red zone. The Utes drove inside the Colorado 10 three times in the quarter and came away with just six points.

A 30-yard catch by Cory Butler-Byrd set up Utah at the Colorado 9 on its first drive of the quarter. The Utes moved down to the Buffaloes' 3 on a 6-yard run from Joe Williams but were forced to settle for a 22-yard field goal from Andy Phillips.

Utah reached the Colorado 14-yard line on the team's next drive. Joe Williams fumbled at the tail end of a long run and the Buffaloes recovered at their own 2-yard line to prevent a possible touchdown.

The Utes got yet another chance to go ahead when Chase Hansen stripped the ball from Liufau near midfield and Chris Hart pounced on the ball. Butler-Byrd gained 41 yards on a reverse to get Utah inside the Colorado 10 once more, but the Utes' offense stalled again. Phillips tacked on another 22-yard field goal to make it 13-13.

Colorado took advantage of Utah's failure to finish. Shay Fields hauled in a 5-yard pass on a fade route to put the Buffaloes back up 20-13. Kyle Fulks set the Utes up in a perfect position to tie it up when he returned the ensuing kickoff to the Colorado 3. Once again, Utah could not move the ball and settled for a 23-yard field goal from Phillips.

"We had our chances," Utah coach Kyle Whittingham said. "You've got to score. You've got to score points, and we didn't do that."

Kenneth Olugbode slammed the door on Utah's comeback effort when he stripped the ball from Joe Williams and returned the fumble 10 yards to put Colorado up 27-16 with 10:56 remaining. Tedric Thompson intercepted Troy Williams -- his second of the game -- on Utah's next possession to keep the Utes from seriously threatening the lead in the final minutes.

Utah closed to 27-22 on a 7-yard touchdown pass from Troy Williams to Demari Simpkins with 1:34 left. Colorado recovered the subsequent onside kick and ran out the clock.

"Worst to first,"Colorado coach Mike MacIntyre said. "Not many people can say they've done that."

Utah set a tone for what would follow by struggling to move the ball throughout the first half. The Utes totaled just three yards on their first two drives. Then, a promising third drive ended with Andy Phillips missing a 45-yard field goal attempt.

Colorado gave Utah plenty of chances to take control early. Kavika Luafatasaga stripped the ball from Liufau on the Buffaloes' opening drive and Pita Taumoepenu recovered it at the Colorado 40. Then, Utah forced a 3-and-out on Colorado's next drive and Boobie Hobbs took the punt back 55 yards for the Utes' first touchdown.

For a while, it appeared Utah's defense and special teams would permanently shift momentum in the Utes' favor.

"That Utah defense is one of the best we've played all year," Liufau said. "It's also a credit to them for how hard they play. Their front is very good and very active. Those linebackers were making some one-on-one plays with our running backs, which is really big."

The Buffaloes settled down before the end of the quarter. Liufau connected with Devin Ross on a 42-yard bomb and raced 12 yards on the next play to get Colorado into the red zone. From there, the senior quarterback punched it in on a 2-yard run to tie it up at 7-7.

Colorado tacked on a pair of field goals from Chris Graham to go ahead 13-7 in the second quarter. The second one, a 19-yarder, came after the Buffaloes stuffed Joe Williams for no gain when Utah went for it on fourth-and-1 at its own 34-yard line. Colorado had a golden opportunity to score a touchdown to cap off the drive, but a wide-open George Frazier dropped a pass on third-and-goal.

NOTES: Utah totaled 86 yards on offense in the first half. ... RB Phillip Lindsay is Colorado's first 1,000-yard rusher since Rodney Stewart in 2010. Lindsay entered the contest with four 100-yard games in his last five contests. ... Boobie Hobbs' 55-yard punt return in the first quarter marked the first touchdown that Utah scored on a punt return this season. ... QB Sefo Liufau eclipsed 2,000 passing yards for the third consecutive season.