BOULDER - A prime time kickoff, an ESPN national TV audience and a change of attire made no noticeable difference for Colorado on Thursday night.

Arizona State broke open a close game with a pair of third-quarter touchdowns - one a momentum-turning 100-yard kickoff return - and frolicked past black-clad CU 51-17 at Folsom Field.

The loss kept the Buffaloes winless at home this season (0-3) and dropped them to 1-5 overall and 1-2 in the Pac-12 Conference. The Sun Devils improved to 5-1 and 3-0 in the Pac-12 South, remaining atop the division.

CU trailed 20-17 at halftime, pulling to within three by scoring 10 points in the first half's final 24 seconds. But the Sun Devils quashed that momentum with Rashad Ross' 100-yard return to open the second half and steadily pulled away from the still-ailing Buffs, outscoring them 31-0 in the final two quarters.

CU coach Jon Embree had said his team could come out of its bye week with the overall cleanest bill of health since the Sept. 1 opener. But that didn't prove to be the case; the injury list was long and costly on a night when the Buffs needed their best players on the field.

Relegated to the sidelines were leading rusher Christian Powell (deep thigh bruise), backup cornerback Yuri Wright (concussion), backup defensive tackle Justin Solis (concussion) and linebacker Paul Vigo (foot).

Top pass rusher Chidera Uzo-Diribe was listed as "out" with a high ankle sprain, but he played in the second half and contributed a quarterback sack.

Safety Ray Polk, who hasn't played since the first quarter of the opener, had hoped to return Thursday night. His pregame status was listed as doubtful and he wasn't in full pads during warm-ups. He didn't play.

As expected, senior linebacker Doug Rippy made his return; he shared time with sophomore Brady Daigh, who was taken from the field on a stretcher with 4:40 remaining after tackling ASU backup quarterback Michael Eubank, a 6-6, 233-pound freshman.

Embree said Daigh, from Mullen High School, was taken to a local hospital for observation. "He had movement in his extremities . . . right now things look OK," Embree said.

ASU rolled up 593 yards in total offense. CU gave up 492 total yards to UCLA in a 42-14 loss in its previous game. With the exception of two first-half drives, the Buffs' offense was stagnant and generated 255 yards - the second-lowest output of the season. CU's running game accounted for 75 yards, but half of that came in the fourth quarter when the visitors had their 34-point lead.

Sun Devils quarterback Taylor Kelly completed 20 of 28 passes for 308 yards and five touchdowns. Buffs quarterback Jordan Webb was 20-of-41 for 180 yards and one TD. He was replaced in the fourth quarter by Nick Hirschman.

The Sun Devils took a 6-0 on a seven-play, 91-yard scoring drive capped by Kelly's screen pass to Marion Grice, who ran 37 yards for the touchdown. It was a play the Buffs would see more than once. Jon Mora's PAT attempt was blocked by Nate Bonsu - and that would be Mora's final extra point try of the half.

Two series later, CU finally mustered enough offense to drive 68 yards in eight plays and take a 7-6 lead on a 2-yard run around right end by Tony Jones - he started in place of Powell - and Will Oliver's extra point.

The "blackout" crowd, many of them late arrivals, sensed a stirring - but it came from the Sun Devils. A pair of swift drives - the first requiring 2:50, the second 1:01 - pushed them ahead 20-7 with 4:24 left in the half.

ASU got its two TDs on a 34-yard pass from Kelly to DJ Foster pass and a 16-yard Kelly-to-Grice toss. After Mora's blocked PAT, the Sun Devils turned to Alex Garoutte for the next two first-half kicks, and he made both.

Down 20-7, CU could have folded. Instead, the Buffs drove 75 yards and scored on a 23-yard pass from Webb to tight end Nick Kasa, who three plays earlier had teamed with Webb for 20 yards on fourth-and-four to keep the march alive.

After Kasa's TD catch across the middle - his third scoring reception of the season - Oliver's PAT brought CU to within 20-14 with 24 seconds before intermission. And the Buffs weren't done.

Justin Castor's kickoff was fielded by ASU's Jamal Miles, but he didn't have possession long. After Daigh jarred the ball loose, K.T. Tu'umalo recovered at the Sun Devils' 19. With 17 seconds left in the half, Webb threw twice for the end zone before Oliver booted a 36-yard field goal on the final play of the half, bringing the Buffs to 20-17.

CU looked to be nicely positioned for the second half, and Embree agreed: "We have a lot of momentum. We're not moving the ball like we want to, but we're getting closer."

But the Buffs' momentum evaporated on the second-half kickoff when Ross sped down the right sideline with Castor's kick and scored. "It just kind of took the wind out of us," CU safety Terrel Smith said. Garoutte's PAT gave the Sun Devils' a 10-point lead - 27-17 - only 11 seconds into the second half.

CU needed a quick response, but the offense wasn't up to it, punting on its first two series. ASU figured it was time to take advantage. Another screen pass from Kelly to Grice - this one covered 20 yards - topped off a 76-yard drive and, after Garoutte's point after, opened a 34-17 ASU lead that carried into the fourth quarter.

CU believed it had earned a break in the first three minutes of the fourth quarter when Smith recovered a fumble, headed for the east sideline and appeared to have a clear path to the end zone.

"It was to the house," Smith said.

But the Pac-12 officiating crew ruled the runner down by contact, nullifying that apparent turnover. A replay review showed otherwise, and CU was awarded the ball at its own 36-yard line. That was little consolation to the Buffs bench, particularly after Smith's fumble return was wiped out.

"The officials should let that go, whether or not he was down and let it play out," Smith said. "I don't understand how they can blow their whistles so quickly. That was going to be a touchdown."

It wasn't, and things got worse, too. After the Buffs offense went three-and-out, Mora returned as ASU's kicker and knocked through a 38-yard field to push the Sun Devils' lead to 37-17 with 9:27 to play.

Just under 4 minutes later, Kelly and freshman receiver Richard Smith collaborated for a 31-yard pitch-and-catch to make it 43-17. Mora, apparently back in good graces after his field goal, kicked the extra point and the Sun Devils had 44 points - six more than their average.

But that figure climbed, too. With 5:38 remaining, Hirschman replaced Webb as CU's quarterback and promptly was intercepted by ASU cornerback Robert Nelson. The Sun Devils turned that pick into a four-play, 54-yard scoring drive, with tailback Cameron Marshall running 14 yards for the score and Garoutte's PAT making it 51-17.

The Buffs' best strategy was to hang onto the ball for the final 31/2 minutes and not allow the Sun Devils another possession. They managed to do that successfully and lose by 34.   

The schedule doesn't ease up either. CU plays its next two games on the road against ranked opponents, visiting No. 11 Southern California on Oct. 20 (4 p.m., MDT) and No. 2 Oregon the following Saturday, Oct. 27 (kickoff time TBA).

Contact: BG.Brooks@Colorado.EDU