STANFORD — So much for building on the momentum gained from the upset of Oregon and the close win at Arizona State.

So much for a spirited defense of its home floor, emerging as a contender in the Pac-12 and sneaking into the NCAA tournament as an at-large team.

Stanford has just one way to make something of its season after an 88-80 loss to UCLA on Saturday at Maples Pavilion, before an announced crowd of 6,562.

It’s the Pac-12 tournament title or bust for the reeling Cardinal, which fell below .500 in league play after being swept by the Los Angeles schools for the second time this season.

“Our goal is to keep fighting,” Cardinal coach Johnny Dawkins said. “There are five games left, and anything can happen in our conference. Our job is to stay focused and understand that we have to get better.”

But getting better probably won’t be enough. The dearth of marquee teams on the remaining schedule limits Stanford’s ability to climb the power ratings and impress the NCAA selection committee.

Realistically, the Cardinal’s only option is to earn the Pac-12’s automatic berth by winning the conference tournament in Las Vegas — a task that will likely require Stanford (15-11, 6-7 Pac-12) to win four games in four days.

The top four teams earn byes into the quarterfinals. The Cardinal, which was picked fourth in the preseason media poll, is tied for eighth in the conference.

“We still want to win as many games as possible,” forward Dwight Powell said. “Our short-term goal is the game ahead of us.

“I’m ready to start watching film on the Oregon (schools) and get ready for the trip.”

The Cardinal has no chance to finish the regular season on an uptick unless it does a better job converting at the rim — a recurring problem in the Dawkins era — and plays tighter defense than it did Saturday.

Fresh off an embarrassing loss at Cal, the Bruins shot 54.4 percent from the field and got 63 combined points from freshmen Kyle Anderson, Jordan Adams and Shabazz Muhammad, whose four-point play in the final minutes sealed the victory.

“When our transition game is going like it was today, sometimes we’re able to slow it down and convert in the half-court,” Anderson said.

Time and again during a free-flowing first half, the Bruins beat Stanford’s defense down the floor for quick-strike baskets.

The easy points allowed Muhammad, Adams and Anderson to find their rhythm and gain confidence.

“Transition defense against UCLA: That’s the No. 1 emphasis,” Dawkins said. “You have to make sure you see the ball. You can’t run back with your head turned, and a couple times, they got us with that …

“Seeing the ball go in helped with what they were doing.”

UCLA (19-7, 9-4) took control midway through the first half, using a 10-2 spurt that coincided with Stanford forward Josh Huestis committing his second foul and taking a seat on the bench.

The Bruins had an answer for every Cardinal rally over the final 30 minutes, whether it was Anderson scoring on a drive, Adams converting underneath or Muhammad draining a jumper.

“We knew we had to bounce back after the disappointing defeat over there in Berkeley the other night,” UCLA coach Ben Howland said. “This is a big win for us, a huge win on the road.”

The game-clinching basket came with 1:52 remaining and the Bruins leading 75-71. Muhammad grabbed a pass from Travis Wear and hit a 3-pointer from the right wing while being fouled by Stanford guard Chasson Randle.

Muhammad made the free throw for a four-point play that gave UCLA a 79-71 lead.

“It always hurts when you foul a jump shooter,” Powell said. “But we’re not going to blame that for the loss.”

For more on college sports, see Jon Wilner’s College Hotline at blogs.mercurynews.com/collegesports. Contact him at jwilner@mercurynews.com or 408-920-5716.