It was arguably the most important game of the season in the Pac-12, and Jaylen Wells delivered. The 6-foot-8 junior from Sacramento, California tied a game-high with 27 points including a critical 4-point play that ultimately put Washington State in front against No. 4 Arizona.

Wells scored 11 of WSU's final 13 points and closed the night on a personal 6-0 run over the last 25 seconds to help the 21st-ranked Cougars dispatch the Wildcats, 77-74.

The victory moved Wazzu (21-6, 12-4 Pac-12) into sole possession of first place in the Pac-12 standings and brought an end to Arizona's unbeaten streak at home that goes back to Feb. 25, 2023. The Cougars ended the Wildcats' previous home winning streak a season ago with a 74-61 victory on Jan. 7 and have defeated Arizona in three of their last four meetings.

It is the first sweep of Arizona for WSU since the 2009-10 season. It is the first time the Cougars are in first place in the conference since 2007.

"This is big," Wells said. "There's a lot of moments we could have folded. We stayed poised, kept fighting back. I think it's a big win for us, because they thought we were the underdog. People saying, 'Oh, you guys gotta go play Arizona.' Nah, they gotta play us. So that's kind of what we thought about.

The Cougars remained mostly in control despite 13 lead changes and a back-and-forth nature throughout the contest Thursday. Arizona (20-6, 11-4) held a lead in the early part of the second half, but a personal 8-0 run from Isaac Jones changed things with just under 11 minutes to play.

The two teams continued to battle from that point, but Wazzu continually had answers for any run put together by the Wildcats.

It was an impressive performance from Smith's squad in a critical matchup for the Cougars.

"Just an incredible win for our program," the WSU head coach said. "Our guys just really gutted it out. I felt like they're really hard to defend, and they opened it up a little bit in the second half with some transition. We hung around just enough, which you want to do on the road.

"Down 3, they really defended us well. We were able to come up with that offensive rebound. Andrej (Jakimovski) had great awareness ... and he found Jaylen. Jaylen got clipped and makes the shot, and kinda what you have to do to win down here. We're very fortunate."

Smith's squad is now in the driver's seat for the Pac-12 regular season title and a No. 1 seed in next month's conference tournament. Plus, ESPN bracketologist Joe Lunardi moved the Cougars up to a 5-seed in his updated projections after Thursday's game.

Seven of the eight players logged minutes for the Cougars scored in the win over Arizona led by Wells, who also had three rebounds and two assists in a game-high 39 minutes. Jones scored 16 points with six rebounds and was 8 for 11 from the free-throw line.

Meanwhile, Rueben Chinyelu chipped in with 12 points and 11 rebounds in 28 minutes off the bench for Wazzu.

The Cougars will look to extend their winning streak to nine games when the meet Arizona State (13-14, 7-9) Saturday at 5 p.m. in the final road game of the regular season.