Provo • Officially, last month’s loss to Gonzaga will go down as the worst, margin-wise, in BYU coach Dave Rose’s 14-year tenure. But Thursday’s collapse against San Francisco was easily the most damaging.

In what was said to be the battle for the No. 2 seed in next month’s West Coast Conference tournament, the Dons rallied from a 14-point deficit with under eight minutes remaining and stunned the Cougars 77-71 in front of 11,484 at the Marriott Center.

Ouch.

With around eight minutes left, after TJ Haws made a 3-pointer to give BYU a 63-49 lead, ESPN’s BPI win probability had the Cougars at 96.9 percent. Then the Cougars crumbled, perhaps more so than at any point in recent memory.

“The last eight minutes were probably as dysfunctional as maybe we’ve looked for quite awhile,” Rose said.

How damaging was this loss?

The Cougars (10-4, 18-11) not only saw their five-game winning streak snapped, they were swept by the Dons (9-4, 21-6) and that could resonate in early March if the teams tie for second place in the WCC standings. BYU has to play at No. 2 Gonzaga on Saturday, while the Dons are finished with the Zags and have a much easier remaining schedule.

“We got to the eight-minute mark, had a 14-point lead, and those are games you should finish off,” Rose said.

After Haws’ triple, the Cougars had a turnover that led to Nate Renfro’s uncontested dunk, and the floodgates opened. Yoeli Childs (28 points, 14 rebounds) missed a free throw, and that miscue was followed by two more turnovers. McKay Cannon missed an ill-advised 3-pointer, and Zac Seljaas missed a trey after yet another turnover.

“San Francisco, they are a great team,” said Haws, who had 25 points in 31 minutes. “I thought they made shots down the stretch. We had a hard time getting the ball in the basket. When you are up 14, you should be able to defend to win that game.”

Gavin Baxter was intentionally fouled with 1:37 left, but officials did not award the Cougars the ball — as they should have done — after he made one of two free throws to tie it at 68-68.

San Francisco’s Jordan Ratinho made his third 3-pointer, on his 11th attempt, to give the Dons a 71-68 lead with 1:20 remaining. After Haws missed a triple to beat the shot clock, Nick Emery intentionally fouled Renfro. This time the officials awarded the Dons the ball after Renfro made one of two freebies.

“Yeah, both [officials] looked at me with a response that looked like they had something in mind [after Baxter was fouled], but when it came to responding they just turned off and went the other direction. So I never really did get a reason,” Rose said.

Charles Minlend and Matt McCarthy made four free throws in the final 24 seconds to seal it.

“This one will sting for a little bit, but we have to move on and get ready for Gonzaga,” Haws said.

Frankie Ferrari led the Dons with 23 points, including 5-of-5 shooting from 3-point range.

“They just had energy and they were making shots,” Seljaas said. “They had the momentum and we just couldn’t get a shot to fall to be able to get it back. They were just rolling, and it is hard to go against that type of energy from a good team.”

The Cougars roared out of the halftime locker room, and took a 53-40 lead seven minutes into the second half after an 8-0 run that included dunks by Childs and Baxter. After Haws’ 3-pointer, his third, they went 4:37 without scoring, and that proved to be their undoing.

“We turned the ball over uncharacteristically, and just with live-ball turnovers, where they could go down and score layups,” Rose said. “You have to give a lot of credit to San Francisco, because they were playing really hard and dong stuff to disrupt us … But I think when we go back and look at the film, we will see a lot of those mistakes were created by our own lack of execution.”

And that film turned into a horror film for the Cougars, worse than the 93-63 beatdown they suffered here to Gonzaga a month ago.