INDIANAPOLIS -- No. 12 seed Oregon State upset the fourth-seeded Oklahoma State Cowboys at Hinkle Fieldhouse 80-70 on Sunday night to advance to the Sweet 16 in the Midwest Regional of the NCAA tournament.

Senior guard Ethan Thompson led the Beavers with 26 points on 5-of-11 shooting and seven rebounds. Oregon State also got a heavy and unexpected lift from junior forward Maurice Calloo, who scored 15 points in the first half. Calloo came into the game averaging 5.2 points.

Oklahoma State star freshman Cade Cunningham, a first-team All-American and projected NBA draft lottery pick, finished with 24 points, 4 rebounds and 3 assists, but the Cowboys rushed shots down the stretch and at times failed to get him the ball.

Though he didn't commit either way when asked if it was his last game, Cunningham spoke as though he is looking beyond college.

"It's been special,'' he said of playing at Oklahoma State. "I think that's the best way to describe it. I think the biggest thing is I surrounded myself around great people. More than anything, that's the thing I'm most proud of. That's the thing, I feel like I've grown up the most by being around good people who pushed me to be somebody good on the court and off the court. I'm going to miss it, for sure."

The Beavers scored 44 points in the first half, the most allowed by Oklahoma State in a first half this season. Their 44-30 halftime lead also represented Oklahoma State's largest halftime deficit of the season. The Cowboys shot 27.7% from the floor for the game, their worst shooting performance since 2014.

"This team had some big goals going into the season," Thompson said after the game. "One of them was winning a Pac-12 tournament championship -- a Pac-12 regular-season championship, as well, of course, but we didn't do that. We got the tournament championship. Ultimate goal is to win the NCAA championship."

Oregon State coach Wayne Tinkle was holding back emotions after the game. His father was a dean of students at Loyola Chicago, the team the Beavers will face in the Sweet 16 on Saturday.

"I grew up on their campus," Tinkle explained.

"Coach [Porter] Moser has done a hell of a job," Tinkle said of the Ramblers. "They're a great team. This is really going to mean something extra special for me and my family."

Oregon State was picked to finish last in the Pac-12 and had to win the conference tournament just to make the NCAA field. The Beavers pulled that off, then cruised past No. 5 seed Tennessee in the first round.

Tinkle took the opportunity during his media availability to speak on the Pac-12, now 6-0 in the NCAA tournament.

"We've got some talented, talented teams in our league," he said. "We're obviously putting everybody on notice. I'm very happy for our program, but I'm extremely happy for the Pac-12 Conference.

"Maybe now we'll get some damn respect."

Oregon State has now won five straight games in elimination settings -- three in the Pac-12 tournament and two in the NCAA tournament. According to ESPN Stats & Information research, the Beavers' BPI chance to win was under 30% in each of those games, and the odds they would win all five were approximately 1 in 2,800.

With Oregon State's win, there will be at least four double-digit seeds in the Sweet 16 for the third time, according to ESPN Stats & Information research. Oral Roberts (15), Oregon State (12) and Syracuse (11) are already in, and (11) UCLA plays against (14) Abilene Christian on Monday.

The Associated Press contributed to this report.