Matthew Knight Arena hasn’t hosted many upsets.

Texas Southern was certainly the most unlikely visitor to leave the arena with a win after stunning No. 18 Oregon 89-84 on Monday night in front of 6,926 who began filing out before the final horn.

“This is a terrible loss,” Oregon junior guard Payton Pritchard said. “A bad loss and this is really where if we are going to turn around our season, it’s right here. Either we move on and get better or we don’t.”

The Tigers (2-4) became the fourth nonconference opponent to beat Oregon in 76 games at MKA since it opened in 2011. Virginia, Mississippi and Boise State were the others.

“No way to sugarcoat it, that was a very poor performance,” Oregon coach Dana Altman said. “We have not had a loss like that here in a long time. We have got a lot of work to do.”

The usual suspects of defense and rebounding were Altman’s prime concerns in the aftermath of the loss. Texas Southern shot 57.6 percent from the field in the second half, including 6-of-11 three-pointers, to outscore the Ducks 57-45 and rally from a 13-point deficit. The Tigers outrebounded Oregon 41-32.

Part of the problem for Oregon (4-2) was the absence of sophomore Kenny Wooten, who suffered a bruised knee with 7:02 left in the first half and did not return. He was on the bench in the second half with ice on his left knee.

“Obviously Kenny is a guy who covers a lot for us, but we can’t lean on Kenny,” Pritchard said. “Honestly, all five guys have got to start defending. That is the way to win.”

The Tigers’ roster features mostly transfers who play one of the toughest nonconference schedules in the nation almost exclusively on the road. Texas Southern opened the season with an upset of Baylor, but dropped its next four games including a 39-point loss at San Diego State and a 37-point defeat at Gonzaga.

Seven-foot-two Trayvon Reed, who played previously at Maryland and Auburn, was 9-for-9 from the field on mostly dunks while adding seven rebounds. Jeremy Combs, a 6-7 senior who transferred from LSU, had 11 points and seven rebounds.

“I was surprised by our effort, especially on the boards, as big and as strong as they are,” Texas Southern coach Johnny Jones said. “We knew that would be a tough task for us, but I thought we did a great job of attacking the glass.”

Bol Bol had 32 points and 11 rebounds while point guard Will Richardson added 13 points and eight rebounds, but no other Oregon player had more than three rebounds.

“We are setting a poor tone on the boards,” Altman said. “People are getting aggressive because they are outrebounding us.”

Texas Southern trailed 39-32 at halftime before scoring on its first three possessions of the second half, including back-to-back buckets by former Oregon State guard Derrick Bruce to close within 41-38.

Bol scored for Oregon and Richardson added a bucket before Paul White made two free throws to put Oregon up 47-38. Bol scored again and Abu Kigab got a basket to cap a 10-0 run that gave the Ducks a 51-38 lead with 16:28 left to play.

“After that, they kind of got what they wanted,” Altman said.

Oregon led 54-44 following a three-pointer by Pritchard before Reed dunked and John Jones made a three-pointer. Jalyn Patterson got Texas Southern within 54-51, but Bol scored on back-to-back possessions to put Oregon back up 59-54.

After Justin Hopkins made a three-pointer, Reed scored on three straight possessions to put the Tigers ahead for the first time at 61-59. Oregon took its last lead at 64-63 when Victor Bailey made a three-pointer, but Patterson followed with a three-pointer and Combs scored to give Texas Southern a 68-64 edge.

The Ducks tied the game 73-73 on a three-pointer by Bol and trailed 79-77 when Richardson made two free throws with 2:07 left to play. Bruce scored on the next three possessions for Texas Southern to take an 85-77 lead following consecutive turnovers for Oregon.

The last hope for the Ducks came when Bol made a three-pointer to cut the lead to 85-82 with 15.1 seconds left to play, but Texas Southern made its final four free throws to secure the upset.