Barely a week ago, Colorado coach Tad Boyle told his Buffaloes they had to be prepared for a game when, "You're not scoring and you have to rely on your defense, you have to rely on your grit and your toughness."

That night came Wednesday, when one of the best shooting teams in the nation struggled all night offensively — and still came away with a 60-53 win over Boise State in the NCAA Tournament First Four at Dayton Arena.

Boyle's 10th-seeded Buffs improved to 25-10 — the most victories in a season in program history — and advanced to a 2:30 p.m. matchup Friday with No. 7 Florida in the South Regional in Indianapolis (TBS).

The Broncos, also a No. 10 seed, ended their season at 23-10. 

Tristan da Silva led CU with 20 points and KJ Simpson recorded a 19-point, 11-rebound double-double. Eddie Lampkin Jr. added 13 points for the Buffs, including a huge basket with 32 seconds remaining that gave Colorado a five-point lead.

Simpson's 11 rebounds were a career high and he scored 15 of his points in the second half, including 10 in the final 5:18.

Chibuzo Agbo led Boise State with 17 points. Tyson Degenhart, BSU's leading scorer, was limited to just six points on 3-for-10 shooting thanks to da Silva's defense.

After leading for much of the game, CU fell behind 49-45 with just 4:31 to play. But Colorado's defense buckled down to produce a four-minute BSU scoring drought while the offense rattled off an 11-0 run, getting four points from Simpson, a 3-pointer from da Silva, Lampkin's tip-in and two free throws from J'Vonne Hadley to seal the win.

"We played with unbelievable toughness," said Boyle, who recorded his third NCAA tourney win in six appearances. "We started to play tougher on the glass and we made just enough plays down the stretch … The Buffaloes have had a helluva year. This team has done some special things."

Both teams struggled shooting the ball all night long. CU finished just 21-for-48 from the floor but shot 11-for-22 in the second half, including 3-for-7 from long range.

BSU shot just 23-for-67, including a 2-for-18 night from beyond the arc.

Boise State did have a 41-31 edge on the boards, including 19 offensive rebounds that produced 19 second-chance points. 

But the Buffaloes' defense in crunch time made the difference, holding the Broncos scoreless in the decisive four-minute stretch in the final minutes.

"I knew it was going to be a battle against these guys," Boyle said. "You just knew from watching film and watching that team all year, they've got some tough-minded guys. They're a quality program. Down the stretch, when we had to, we got rebounds. I thought KJ's 11 rebounds obviously stand out and our guys battled. These guys did what they had to do down the stretch and beat a tough, hard-nosed team."

HOW IT HAPPENED: Colorado led by two at the half, 26-24, then quickly built the margin to seven. 

Simpson started a 9-2 run with a basket inside before da Silva drained a long 3-pointer, just CU's second trey of the game. Lampkin followed with a basket inside after a BSU bucket and Simpson scored again underneath to give the Buffs a 35-28 lead with just under 16 minutes still to play.

But the Broncos wouldn't go away. BSU forged a 9-3 surge to close the gap to 38-37 with 12:54 remaining, then used an 8-0 run to take a 47-43 lead with 5:40 on the clock.

Colorado then fought back to regain the lead. Simpson recorded a steal and basket, da Silva hit another 3-pointer and Simpson hit two free throws to give the Buffs a 50-49 lead with 3:42 to play.

"Basketball is more than offense," Simpson said. "Obviously it wasn't my best night shooting the ball. That was kind of frustrating. So I wanted to go out there and be a leader and go get rebounds and do whatever the team needed for me to do … But I knew eventually something was going to fall for me. And down that stretch I needed to make a big play, and I was ready to step up to it."

The Buffs then notched a defensive stop and Simpson scored on the other end again for a 7-0 CU run and 52-49 Colorado lead with 2:40 to play.

CU's defense continued to step up over the final minutes. The Buffs produced back-to-back defensive stops to stretch a Boise State scoring drought to four minutes before Lampkin tallied maybe the biggest bucket of the game. After Hadley missed a short jumper, Lampkin just beat the shot clock with a tip-in to give CU a 54-49 lead with 32 seconds remaining.

"It was huge," da Silva said. "He's a beast on the glass, and we really needed him tonight to match their physicality. It was a great play. Got it up in time and got us up five."

CU then forced a BSU turnover and Hadley hit two free throws with 24 seconds remaining to seal the victory.

Boise State's Degenhart entered the game averaging 17 points per game but was never a factor on the offensive end as da Silva bottled him up all night.

"He was the focus of the scouting report and I knew I'd have my hands full the whole game," da Silva said. "He's a great player. He's taken Boise to three consecutive NCAA appearances. I knew I had to step up my game defensively for this one specifically."

Colorado took a 26-24 lead into the halftime break after a defensive-dominated first half that featured five lead changes.

Boise State led early, using a 7-0 run to take a 13-9 lead after the Buffs came up empty on five straight possessions. 

But Colorado battled back, finally taking a 15-14 lead on a Simpson drive with 6:50 to play in the half. The Buffs extended the lead to six on 24-18 four minutes later on a Luke O'Brien three-point play before BSU shaved Colorado's lead to just two at intermission.

DECISIVE STRETCH: After falling behind by four with less than five minutes to play, Colorado put together an 11-0 run to take a 56-49 lead with just 24 seconds on the clock.

WHAT IT MEANS: The Buffs picked up a big NCAA Tournament win while also setting the program record for victories in a season (25).

KEY STATISTICS: CU finished just 21-for-48 from the floor but shot 11-for-22 in the second half, including 3-for-7 from long range … BSU shot just 23-for-67, including a 2-for-18 night from beyond the arc.

NEXT UP: Colorado will travel to Indianapolis for a 2:30 p.m. game Friday against No. 7 Florida in the South Regional (TBS).