With the college football season ending Monday, college basketball took center stage Tuesday — and immediately saw its top two teams suffer upsets at the hands of unranked opponents.

No. 1 Purdue fell at Nebraska 88-72, while No. 2 Houston lost its first game of the season at Iowa State 57-53.

According to ESPN Stats & Information, it was the first time since Feb. 6, 2016, that the top two teams in the AP men’s college basketball poll lost to unranked opponents on the same day, and only the eighth time in the poll’s history.

The Boilermakers entered Tuesday on a seven-game winning streak, including victories over Arizona, Illinois and Alabama. But Nebraska matched them shot for shot in the first half and finished the opening period on a 13-0 run to lead by 11 at halftime.

Purdue cut Nebraska’s lead to one within the first six minutes of the second half, but the Cornhuskers immediately responded with a 14-2 run to take their biggest lead of the game with 11:53 remaining. Purdue wouldn’t get closer than six points the rest of the game, and Nebraska finished on an 11-2 run.

„That was the difference in the game,“ Purdue coach Matt Painter said of Nebraska’s halftime lead. „We had a couple good fights there in the second half to where pulled within single digits and one time we got it to two, then they pushed it right back to double digits.“

The Cornhuskers shot 14-for-23 from 3-point range as a team, with seven players making a shot from behind the arc. Keisei Tominaga led the way with 19 points, while Rienk Mast had 18.

It was Nebraska’s first win over an AP No. 1 team since Feb. 6, 1982, and its fourth such win in program history. The first came March 3, 1958, under coach Jerry Bush, grandfather of current coach Fred Hoiberg.

„It doesn’t get much bigger than this one, the No. 1 team, the reigning national player of the year,“ Mast said. „I just see that as a challenge and luckily, the shots were going in in the beginning and gave the team a little spark and everybody started believing.“

Tuesday marked the fourth time in the past two seasons that a No. 1-ranked Purdue team has lost to an unranked opponent. Last season, the Boilermakers fell to Rutgers and Northwestern. Earlier this season, they again lost at Northwestern.

Purdue becomes just the second team in AP poll history to lose multiple games as No. 1 to unranked opponents in consecutive seasons, the other being North Carolina in 1985-86 and 1986-87, according to ESPN Stats & Information.

Earlier in the night, Houston became the last team in men’s college basketball to lose a game this season, falling at Iowa State in the Cougars‘ first conference road game as a member of the Big 12.

Kelvin Sampson’s team was introduced quickly to „Hilton Magic“ as the Cyclones jumped out to a 14-0 lead and forced 12 first-half turnovers.

„I don’t know if it was as much Iowa State. It was us,“ Sampson said. „We were just, I don’t know what. I wish I did.“

Iowa State led the entire first half, but a 7-0 Houston run forced a 41-41 tie with 10:48 remaining. Neither team led by more than five points the rest of the way, with Houston taking its only lead of the game on a Jamal Shead jumper with 3:17 remaining.

With the game tied at 53 in the final minute, Iowa State freshman Milan Momcilovic caught the ball along the left baseline, turned and hit a contested fadeaway over two Houston defenders to give the Cyclones a two-point lead. Momcilovic would ice the game with two free throws with 10 seconds left.

„It was important that we came out and set the tone with the game,“ Iowa State coach T.J. Otzelberger said after the game. „We talked about we need to throw the first punch, we need to be the aggressor, we need to be the team that sets the tone. And I think we set the tone right away. Certainly, there was points in the game where it almost felt like we were hanging on, but I think our guys were able to dig deep. I think it was setting the tone and being the aggressor, and then it was just a group of guys who are really connected and had resolve.“

The losses by Purdue (14-2) and Houston (14-1) open the door for No. 3 Kansas (13-1) to return to No. 1, where the Jayhawks opened the season. Bill Self’s team, which received two first-place votes in this week’s AP Top 25 poll, plays at UCF on Wednesday night before hosting No. 9 Oklahoma on Saturday.

The Associated Press contributed to this story.