PORTLAND — BYU coach Mark Pope had witnessed it firsthand before. Twice, actually.

As an assistant with the Cougars almost a decade ago, he had seen Oregon’s length and athleticism and explosiveness. He knows all about how the Ducks crash the glass, force turnovers and race up and down the court in transition.

It’s the stuff nightmares are made of.

In his first tour of duty at BYU, it happened once during a defeat in Eugene to a nationally ranked Duck team and, later in the same season, a loss in the NCAA Tournament to Oregon.

So going into Tuesday’s huge matchup against the No. 12 Ducks, Pope was wary, and he knew what his team needed to do to overcome Oregon’s strengths in order to pull off a major upset.

What occurred at the Moda Center in the Phil Knight Invitational had to exceed anything he could have imagined, as he he saw the Cougars out-Oregoning Oregon by controlling the boards and dominating in the paint.

Oh, and it helps to shoot a scorching 59.6{362bf5cdc35eddfb2532d3c23e83b41deb229c4410d15cb1127c60150cbd4488} from the floor.

In the end, BYU dismantled and shell-shocked the Ducks 81-49 on national television — and the Cougars did it primarily with defense and rebounding.

It wasn’t just how they won, it was that they made it look easy. BYU never trailed in the game and it cruised to a 19-point halftime lead.

And it was a historic victory.

According to ESPN, the Cougars are the first unranked team to beat a top-15 team away from home by 30-plus points since 1993, when UConn walloped Virginia. The 32-point win is the largest margin of victory against a ranked opponent in the AP Poll era, dating back to 1948.

Not only did BYU (3-0) outscore Oregon (2-1) in the paint, 42-28, but it outrebounded the Ducks 35-25 and it outscored them in points off turnovers 18-5.

“We’re super excited about the result tonight. We have so much respect for this Oregon team … This is a great team, an incredibly potent offensive team. We knew that we were going to have our hands full defending the glass and trying to guard these guys. They can do everything on the court,” Pope said.

“Our guys did an unbelievable job fighting on the glass. We knew it was a huge challenge for us … We did a great job of all the ways where they normally fix the game, when it’s not going right, we were really good about saying, ‘We’re not going to let you fix it that way. You’re going to have to fix it the hard way.’”

After the game, Oregon coach Dana Altman looked like he had just awoken from a nightmare, like the one in which you’re walking around school in your underwear.

“I don’t want to take anything away from BYU. They outworked us, they out-prepared us. They played very well. They got what they wanted,” Altman said.

“Getting beat by 30 points, that hadn’t happened to us in, I don’t know, and it shouldn’t happen to our program. I’m totally embarrassed.”

BYU senior guard Alex Barcello, who scored a game-high 25 points, hit 9 of 11 shots, including 4 of 6 from 3-point range, expounded on the magnitude of this win.

“Every win means a lot to us. Obviously, this was a pretty highly ranked team. A lot of talented guys,” he said.

“This is definitely a huge win for us and starting off the season 3-0. That’s what all of us would have wished for a few months ago. Now that we’re here, it’s definitely great to have those three wins under our belt. It’s a really big win for us.”

And it was no fluke.

The Cougars controlled the game from the opening tip, taking an early 6-0 lead. In the first half, BYU shot 16 of 28 (57{362bf5cdc35eddfb2532d3c23e83b41deb229c4410d15cb1127c60150cbd4488}) from the floor while holding Oregon to 5 of 25 (19{362bf5cdc35eddfb2532d3c23e83b41deb229c4410d15cb1127c60150cbd4488}) and was up 37-18 at halftime.

Amazingly, the Cougars actually shot even better in the second half — 18 of 29 (62{362bf5cdc35eddfb2532d3c23e83b41deb229c4410d15cb1127c60150cbd4488}).

“We were expecting Oregon to make a run, for sure, because they’re such a great team,” Barcello said. “But I think what gave us the most energy was our defense and rebounding because Oregon is such a great rebounding team. That was our main focus, to protect the middle.”

Pope was happy to see Barcello show what he can do on a big stage.

“There are just no words left for this guy. I know the country hasn’t seen him. I don’t know exactly why because we’ve been really good the last two years,” he said. “This is Alex Barcello. This is what he does. He goes on the road against the No. 12 team in the country.

“He goes 9 for 11 and not just 9 for 11, but he does it 100{362bf5cdc35eddfb2532d3c23e83b41deb229c4410d15cb1127c60150cbd4488} in the context of how we play. He’s not breaking things off or going into isolation. He’s not forcing shots. He’s become a master of what we try to do.”

Meanwhile, BYU had contributions up and down the roster.

Te’Jon Lucas chipped in 12 points while Fousseyni Traore had a career-high 10 points, six rebounds and two blocked shots.

Spencer Johnson scored 10 to go along with three assists and Gavin Baxter had seven points, five rebounds and two blocks.

Seneca Knight added nine points, six boards and three assists.

“That’s the fun thing about being on a team with such highly talented guys. Everybody can play. It doesn’t matter how many minutes they get in a given game. They’re all ready to go,” Barcello said.

“It’s been fun to watch our team as these games have gone on, everybody is pushing aside their own agenda, which is really special. That’s why we won by so much tonight — nobody was worried about how many minutes or shots they were getting, what their stats were like. We were just focused on winning.”

Late in the game, the Cougars continued their relentless play. With less than six minutes remaining, Trevin Knell stole the ball and passed it to Johnson, who fed Gideon George for a resounding dunk.

At that point, the Cougars led 70-44.

Moments later, the lead increased to 74-48, and while Oregon fans exited the Moda Center as if a fire alarm had sounded, BYU fans started chanting, “B-Y-U!”

In football, the Cougars are 4-0 so far this season against Pac-12 opponents, and Tuesday, BYU started the season in dominating fashion against the Pac-12 in basketball, too.

If you can’t join ‘em, beat ‘em.

And the Cougars made the Big 12 look pretty smart, as they’ll join that league in 2023.

But for now, as a member of the West Coast Conference, BYU looked awfully good in knocking off the No. 12 team in the country.

The Cougars likely will be ranked next week.

BYU hosts Central Methodist Saturday, and both Barcello and Pope stressed the need to continue to get better as a team.

Still, Tuesday’s historic win on national television at the Moda Center will loom larger as the season goes on in terms of the Cougars’ NCAA Tournament resume, and it was an outcome they won’t soon forget.

Neither will the Ducks, who got beat at their own game.