Steve Alford says UCLA’s game against Oregon State on Friday is a must-win

Going from unbeaten overall to winless in the Pac-12 Conference has changed the dynamic for UCLA. A midseason game against middling Oregon State on Friday night at Gill Coliseum has taken on new meaning.

“That’s a must-win for us,” Bruins Coach Steve Alford said Wednesday after his team dropped its conference opener to Oregon, 89-87, on a three-pointer in the final second for its first defeat of the season.

Second-ranked UCLA finally encountered a team that could match it offensively, the No. 21 Ducks hurting the Bruins in transition and on the perimeter while building a 12-point lead in the first half. The Bruins rallied largely because they tightened their defense before faltering over the final 3 1/2 minutes, which coincided with Oregon’s game-ending 15-5 run.

“You can’t be that you’re up six or seven and you think that the game’s over,” Alford said. “You’ve got to finish.”

The Bruins didn’t end the game with their usual four-guard lineup, presumably in part because center Thomas Welsh was playing well in his return from a bruised right knee and in part because of the continued struggles of guard Isaac Hamilton. Hamilton made only one of six shots, had three turnovers and committed a foul early in the second half that appeared to incense Alford. Hamilton has made two of 18 three-pointers over his last four games.

UCLA players and coaches alike said they were eager to see how they would respond to their first loss of the season after a 13-0 start.

“I think it’s good that we have some adversity,” said guard Bryce Alford, who missed the front end of a one-and-one opportunity at the free-throw line with 8.9 seconds left and his team ahead by one point. “This team needs some adversity to go through, but you never want to lose a game and we had this game. We feel like we kind of blew one at the end, but we’re very confident we can bounce back.”

Guard Lonzo Ball, who suffered his first defeat since the state championship game at the end of his junior season at Chino Hills High, did not speak with reporters afterward but appeared to be relatively upbeat, according to Welsh.

“He was telling us to keep our heads up, just get ready for the next one,” Welsh said, “because it’s one of those things that happens in sports and obviously it’s his first loss in a while but we’ve just got to get ready for the next one now.”

UCLA AT OREGON STATE

When: 8 p.m., Friday.

Where: Gill Coliseum, Corvallis, Ore.

On the air: Pac-12 Networks; Radio: 570.

Update: The Beavers (4-10 overall, 0-1 Pac-12 Conference) have sputtered since leading scorer Tres Tinkle suffered a broken hand late last month, going 2-6. Tinkle is not expected to return until next week. Oregon State is coming off a 70-63 loss to USC in which the Beavers fell behind, 24-9, and didn’t help themselves when Drew Eubanks earned a technical foul for stepping on the Trojans’ Charles Buggs after Buggs fell to the court in the second half.

And then there was one

USC’s Charles Buggs (1) and Jordan McLaughlin (11) walk away from a small scuffle against Oregon State in the second half on Dec. 28.

(Anibal Ortiz / Associated Press)

UCLA’s loss left USC as the only undefeated team in the Pac-12. But for how long?

The No. 22 Trojans will face Oregon on Friday night at Matthew Knight Arena, where the defending conference champion Ducks have won 34 consecutive games.

“It’s a tough environment to play in,” USC Coach Andy Enfield said Thursday. “When [Nike founder] Phil Knight shows up courtside at the game, it makes it even tougher. But we’re looking forward to the challenge.”

Already without forward Bennie Boatwright because of a serious knee injury, the Trojans nearly lost point guard Jordan McLaughlin on Wednesday when he took an elbow to the face against Oregon State, leaving one eye swollen and bloodshot. McLaughlin persevered, finishing with 10 points, eight rebounds, four assists and four steals while taking only two shots during USC’s 70-63 victory.

“Pretty good for a guard who couldn’t see out of one eye,” said Enfield, who expected McLaughlin to feel better for the game against the Ducks.

Enfield acknowledged that he didn’t foresee the Trojans going 14-0 with or without Boatwright but didn’t think that record placed any strain on his team to remain unbeaten.

“I know our coaching staff doesn’t feel any pressure and I don’t think our players do either,” Enfield said. “We know we have a long season, the Pac-12 is one of the best leagues in the country and every game we play in the league now is going to be difficult and challenging, so I don’t think there’s any more or less pressure than there was at the beginning of the season.”

USC AT OREGON

When: 7 p.m. PST, Friday.

Where: Matthew Knight Arena, Eugene, Ore.

On the air: TV: FS1; Radio: 710.

Update: USC is trying to complete a road sweep of the Oregon schools for the first time since the 2007-08 season after being swept the previous six times the Trojans traveled to the state. Oregon Coach Dana Altman did not sound satisfied even after his team prevailed, 89-87, over second-ranked UCLA on Wednesday night. “We better be a better team Friday night, “ Altman said after the Ducks shot 34.4% in the second half against the Bruins, “because we’re going to have a heck of a battle.”

ben.bolch@latimes.com

Twitter: @latbbolch