LAS VEGAS — Oregon State rallied from a 12-point fourth quarter deficit, then outlasted Colorado in double overtime, beating the Buffaloes 85-79 Thursday in a Pac-12 women’s basketball quarterfinal.

A.J. Marotte hit a short jumper with 1:46 left to give fourth-seeded OSU the lead, and the Beavers managed to build from there in ousting the Buffaloes from the tournament in MGM Grand Garden Arena.

Oregon State, trailing 50-38 with 7:30 left in regulation, stormed from behind to force overtime. The Beavers finally took control when Marotte’s basket triggered a run of eight consecutive points that Colorado could not overcome.

Oregon State (24-6) advances to the tournament semifinals, where it plays the Stanford-California winner at 6 p.m. Friday.

It was the first-ever double overtime game in Pac-12 women’s basketball tournament history. Oregon State’s 85 points was a school record for the conference tournament.

The Beavers rode the broad shoulders of sophomore Raegan Beers, who scored 27 points and set a school tournament record with 12 field goals. Beers also had a team high 13 rebounds. Timea Gardiner, Donovyn Hunter, Dominika Paurova and Talia von Oelhoffen each scored 13 points each for Oregon State. Gardiner collected 11 rebounds, while Hunter had nine assists, an OSU tournament record.

Jaylyn Sherrod scored 23 points and Aaronette Vonleh 20 to lead the fifth-seeded Buffaloes (22-9).

Oregon State couldn’t buy a basket outside of a layup for the game’s first 15 minutes. The Beavers made only 6 of their first 23 shots — five on layups — as Colorado took a 23-12 lead.

But Hunter gave OSU’s shooting some life. She hit a 15-foot jumper. Then Beers followed by a free throw-line jumper. It triggered a 10-0 run as the Beavers pulled to within a point before Colorado scored late to take a 25-22 halftime lead.

Oregon State began to warmup early in the third quarter. Beers and Hunter each hit shots as the Beavers took their first lead of the game at 27-25. But Colorado regrouped, finishing the third quarter with an 11-3 run to take a 45-36 lead.

Colorado stretched its lead to 50-38 early in the fourth when Oregon State found life. Talia von Oelhoffen and Gardiner hit back-to-back threes to ignite an 11-0 run. Von Oelhoffen’s layup with 4:27 left gave the Beavers a 51-50 lead. Then with 1:08 remaining, Gardiner hit a pair of free throws to tie the game at 53. Both teams had a chance to take the lead during the final 30 seconds of regulation, but came up short.

Colorado scored the first five points of overtime, but the determined Beavers rallied again, taking a 60-59 left on a Hunter drive with 39 seconds left. Then, with the game tied at 63, OSU had a chance to win it, but von Oelhoffen’s runner at the buzzer fell short.

In double overtime, OSU outscored Colorado 22-16, scoring most of the points during the final 90 seconds.

• You can watch every game of the women’s Pac-12 basketball tournament live with Fubo (free trial) or with Sling (promotional offers, cheapest streaming plans) if you don’t have cable.