BOULDER -- Washington State forged a lead early and never looked back handing No. 17 Colorado its first defeat of the season, 47-26, at Folsom Field on Saturday.
Sammy Moore caught a 74-yard touchdown pass and returned a kickoff 97 yards for another score as Washington State used big plays to down the Buffaloes (2-1), who had five turnovers.
The Cougars (2-1), who led 23-13 at halftime, scored 24 straight points in the first 6:39 of the third quarter to build a 47-13 lead. Two scores came off turnovers.
Matt Kegel threw three touchdown passes for Washington State, including a 77-yarder to Scott Lunde, and cornerback Jason David returned an interception 41 yards for another TD.
Kegel said his 74- and 77-yard touchdown passes came when Colorado was blitzing, leaving one-on-one coverage on the receivers.
Colorado backup Erik Greenberg, replacing injured starter Joel Klatt, threw for three scores. Klatt missed two series in the first half after bruising his throwing shoulder and departed for good after reinjuring the shoulder on a sack by linebacker Don Jackson early in the third quarter.
Washington State seized the momentum on the first play of the second half. Moore fumbled the kickoff near the goal line, but picked it up and sprinted to his left and down the sideline for a 97-yard scoring return.
After a Colorado punt, WSU needed just five plays to score again. Jonathan Smith broke six tackles en route to a 26-yard run off the right side.
Two plays later, Klatt was sacked by Jackson and fumbled, giving the Cougars possession at the Colorado 12. Kegel promptly hit Devard Darling on a 12-yard scoring pass.
Three plays later, safety Erik Coleman intercepted Greenberg and returned 14 yards to the Colorado 25, setting up Drew Dunning's 39-yard field goal for a 47-13 lead.
Greenberg capped a 73-yard scoring drive with a 1-yard TD pass to Derek McCoy late in the quarter, then added a 2-yard TD pass to Joe Klopfenstein.
"The kickoff return took the air out of us," Buffs head coach Gary Barnett said. "We had about four big mistakes that put us in such a hole, and that team was too good to come back against."
With Klatt doubtful for next week's game at Florida State, Barnett said Greenberg likely will start.
The Cougars took a 20-6 first-quarter lead on two long TD passes and David's interception return.
Less than five minutes into the game, Kegel threw over the middle to a wide open Moore, who broke two tackles near midfield and completed a 74-yard scoring play.
Colorado countered barely a minute later. Klatt threw a 33-yard pass to Jeremy Bloom, setting up a 3-yard toss to Klopfenstein, but Mason Crosby's extra-point attempt was blocked by Steve Cook.
The Cougars added two touchdowns just 1:24 apart late in the quarter.
On third-and-3, Lunde slipped past the secondary and caught Kegel's pass at the 50 for a 77-yard scoring play. Dunning's PAT hit the left upright.
Greenberg replaced Klatt on the next series and, on his fourth play, threw into the left flat, where he was intercepted by David, who returned 41 yards for a touchdown.
Greenberg got the Buffs within a touchdown early in the second quarter, hitting McCoy on a 46-yard scoring pass.