PULLMAN, Wash. -- Jordan Webb scored on a 4-yard run in the final seconds, the last of three Colorado touchdowns in the final 7 minutes, to beat Washington State 35-34 on Saturday in the Pac-12 Conference opener for both teams.

Webb threw for two touchdowns and ran for two more for Colorado (1-3), which had been outscored by an average of 40-19 coming into the game.

Connor Halliday threw four touchdown passes for Washington State (2-2), which was looking for its first three-game winning streak since 2006.

Washington State was ahead 34-28 when Colorado took over on its 30 and marched to the WSU 4. On fourth down, Webb bootlegged up the middle for a touchdown to tie the score. Will Oliver's extra point gave Colorado its first lead, 35-34, with 9 seconds left.

Colorado had pulled within 31-28 on Webb's 70-yard touchdown pass to Nick Kasa midway through the fourth quarter, followed by Tony Jones' 84-yard scoring run with 4:23 left. On the ensuing kickoff, the Cougars wasted Teondray Caldwell's 56-yard return and had to settle for Andrew Furney's 42-yard field goal. That set up Webb's final drive and touchdown run.

The game was played in air thick with smoke from wildfires 200 miles away in central Washington.

Washington State was coming off narrow wins over Eastern Washington and UNLV, and has so far shown only flashes of new coach Mike Leach's high-flying "Air Raid" offense.

Washington State scored on its first possession, when a scrambling Halliday hit Gabe Marks in the end zone with a 32-yard pass for a 7-0 lead. Colorado replied with a crisp 75-yard drive that ended when Webb connected with Nelson Spruce on a 16-yard touchdown to tie the score. Webb completed all five of his passes on the drive.

Halliday was intercepted near the Colorado goal line by Jered Bell on WSU's next possession. Colorado's drive stalled at WSU's 13 and Will Oliver missed the 30-yard field goal attempt.

Marquess Wilson caught a 23-yard scoring pass from Halliday as WSU took a 14-7 lead early in the second quarter.

Colorado fumbled the ball away at its own 39 on its next possession. Halliday's 15-yard touchdown pass to Isiah Myers put WSU ahead 21-7 with 11:48 left in the first half. The drive was kept alive when Halliday hit Myers on fourth-and-8 for an 11-yard gain.

In the third, Carl Winston fumbled deep in WSU territory on the Cougars' first possession, and Terrel Smith picked the ball up on the 10 and ran it down to the 1. Webb ran the ball over on the next play as Colorado closed to within 21-14.

Furney missed a 53-yard field goal attempt for WSU on their next possession.

Daniel Simmons intercepted Webb on the next series, and Halliday threw a short pass to Wilson, who turned it into a 49-yard touchdown reception and a 28-14 lead for Washington State.

A shanked punt gave WSU possession on Colorado's 30, but the Cougars couldn't move the ball and settled for Furney's 45-yard field goal and a 31-14 lead early in the fourth, setting the stage for the Buffaloes' comeback.