BOISE -- Chalk it up to beginner's luck or the madness of March, Idaho State will just call it a win.

For the first time in a long time, the Bengals survived and advanced.

No. 11 seed ISU upset No. 6 Northern Arizona 64-62 in the first round of the Big Sky Conference men's basketball tournament Wednesday, the program's first postseason win since 2009. The Bengals (8-22) advance to Thursday's quarterfinal round, where they face No. 3 Montana at 8 p.m. at CenturyLink Arena.

"Extremely happy for our guys," first-year ISU head coach Ryan Looney said. "We've had a lot of disappointing moments so far this year. ... I think we corrected some big things in this game, finally."

The win was bolstered by a hot-shooting first half, Austin Smellie's 16 points, Chier Maker's 15 points and 12 rebounds and Malik Porter's 12 points off the bench. The Bengals led by 15 points at halftime and hung on down the stretch, becoming the second 11-seed to win a Big Sky tournament game since the field expanded to include all conference teams in 2016.

"We feel good about it," Porter said. "We wanted to get the win, celebrate today, move on, focus on Montana."

ISU vanquished recent late-game struggles in preserving the win.

First, Austin Smellie made two free throws with 6.2 seconds remaining to give ISU a 64-61 lead. Then, the Bengals fouled the Lumberjacks, instead of letting them get a look at a game-tying 3-pointer, sending Cameron Shelton to the free-throw line with 3.0 seconds left.

Shelton made the first free throw and missed the second on purpose, hoping he or a teammate could secure an offensive rebound and score a quick 2.

But ISU got the board to seal the win and the upset.

ISU has failed to execute late-game scenarios like those multiple times this season, missing free throws, missing a box-out or committing a turnover to let the other team steal a win. The Bengals put it all together on Wednesday, showing the late-game poise that was seldom there during their first 29 games.

"Eight times, we were in games similar to today, whether we had a lead and gave it up or were behind and came back," Looney said. "And every one of those games, we found a way to lose by a possession late."

The final script nearly looked different.

NAU (16-14) scored the first 13 points of the second half, cutting ISU's 44-29 halftime lead to 44-42. After shooting nine 3s in the first half, the Lumberjacks hammered the ball into the paint out of halftime. Bernie Andre and Cameron Satterwhite converted layups-plus-free throws, and Andre capped the run with a 3.

ISU missed its first five shots of the half until Malik Porter ended the drought with a layup, pushing the Bengals' lead back to two possessions at 46-42.

Another Andre 3 tied it 50-50 with 11:16 remaining, but ISU answered with a 7-0 run. NAU hung around though, climbing back within three points, 57-54, at the 6:59 mark.

Brooks DeBisschop completed a three-point play to bring NAU within one, 62-61, with 3:00 to go. Neither team scored again until Smellie's late free throws, as they combined to miss their final eight field-goal attempts of the game.

"Really proud of our guys, how we fought back," Lumberjacks interim head coach Shane Burcar said. "To be down 15 at the end of the first half ... it's something that I knew we could overcome, and we came out and battled in the second half."

The Bengals shot 58.1% in the first half, draining 7 of 12 shots from the arc. Maker scored all 15 of his points in the period and Smellie went 3 for 5 on 3-pointers, helping ISU bounce back from an early 11-2 deficit.

ISU closed the half on a 13-0 run, during which Smellie, Nico Aguirre and Maker all hit a 3.

"We had multiple players shoot it well in the first 20 minutes," Looney said. "But also, as time has gone on, we've played more and more unselfishly on offense, too. Because of our ball movement, we were getting much more open shots than maybe what we were getting earlier in the season."

The 15-point lead helped cushion ISU's second-half offensive struggles. NAU's press made it hard for the Bengals to get into their offense, as players forced drives to the hoop or rushed 3s instead of playing through their swing offense.

Porter benefited from the no-longer free-flowing offense, scoring eight of his 12 points in the second half on 4-of-8 shooting. The 6-foot-5 junior posted up the 6-foot-9 DeBisschop, using his athleticism to maneuver his way around and over his bigger defender.

The Bengals needed each bucket. They shot 27.6% and scored 20 points in the half.

"Just having that mamba mentality, coming out aggressive in the second half," Porter said. "I wanted to make my teammates better, being aggressive, making the extra passes. That's what we did in the first half."

DeBisschop did the bulk of his damage early, starting 5 for 5 from the floor on easy buckets down low. ISU switched multiple defenders onto NAU's big man, and his production finally slowed down when ISU fronted him in the post and forced NAU to score from outside.

DeBisschop finished with 17 points and 11 rebounds, going 3 for 9 after his 5-for-5 start.

ISU and NAU played three times this season, each matchup featuring a double-digit second-half lead, a second-half comeback and a final margin of four points or fewer.

NAU is the only team ISU has beaten twice this season.

"For whatever reason, when we've played them, we haven't come out with good intensity for a full 40 (minutes)," DeBisschop said. "Whenever you don't play as hard as you can for a full game, there's going to be back and forth."

Up next:

ISU plays two-time defending tournament champion Montana (18-13) at 8 p.m. Thursday in the tournament quarterfinals. Montana is 2-0 against ISU this season and has won the last 19 times head-to-head.

Notes:

- During the game, the NCAA announced that this year's Division I men's and women's basketball tournaments will be held without fans in attendance in light of the progression of COVID-19.

"I have made the decision to conduct our upcoming championship events ... with only essential staff and limited family in attendance," NCAA President Mark Emmert said in a statement.

Looney, Porter and Maker weren't aware of the news until they were asked about it during Wednesday's postgame press conference.

"Gotta think about the safety and well-being of everyone," Looney said. "I think our guys would be excited to keep playing, whether there was 20,000 people in the stands or zero."

"It'd be hard," Porter said. "That's what I'm playing for, all the fans and my family and the coaches. But I'm going to go out and play for my teammates and play hard."

IDAHO STATE 64, NORTHERN ARIZONA 62

ISU 44 20 -- 64

NAU 29 33 -- 62

ISU -- Maker 15, Smellie 16, Cool 7, Udengwu 4, Stutzman 5, Porter 12, Rushin 2, Aguirre 3.

NAU -- Andre 16, DeBisschop 17, Satterwhite 7, Shelton 13, Avdalovic 7, Bowling 2.