Faisal Aden writhed underneath the basket in blinding pain.

Perhaps the only one in McKale Center to see the Washington State guard was the television cameraman, who filmed him from a foot away while sitting in a swivel chair.

Play continued on the other side of the floor for maybe 10 seconds.

"I didn't see until we started going the other way," WSU coach Ken Bone said after the Cougars' 85-61 loss to the Arizona Wildcats. "Arizona got the ball and nine guys came in one direction.

"He stayed down there."

It wasn't stopped until the Arizona Wildcats led a half-speed fast break back toward Aden.

The senior guard injured his left knee while leaping for a layup into UA guard Jordin Mayes.

Replays showed Aden's knee bending in an unnatural way, bowing toward his right leg.

He was diagnosed with a sprained left medial collateral ligament. Bone said he was unsure about the senior guard's timetable. Bone doubted he would play Saturday. The injury could linger much longer.

"I hate to see anybody get injured," he said, "especially when it's a game-ending injury that is potentially more than one game."

The Cougars struggled mightily without the reigning Pac-12 Player of the Week, but Bone said that wasn't the only contributing factor.

"The way Arizona played tonight, I'm not sure it would have made any difference," he said. "It definitely didn't help us, because he's played such good basketball as of late - and scored the ball extremely well as of late."

And the Cougars (11-9, 3-5) need scorers.

"It's hard to replace someone, especially on the week he came off, such confidence," said forward Brock Motum, who finished with 18 points, the only WSU player to top nine. "It's very hard to replace the scoring load."

When Aden left the floor with 4:02 to play, the Cougars trailed, 30-22.

The Wildcats went on a 12-5 run the rest of the half, scoring the final 10 points of the half.

They started the second half on fire, scoring 11 of the first 16 points.

"Looking at it, when we're having games like this when you're on the road, you have to play possession by possession," said guard Marcus Capers, who had two points. "I felt like, even me a couple times, I tried to get everything done in one possession.

"This is not a football game where you can sit down and stop and set a play up, you know what I'm saying?"

Aden was named Pac-12 Player of the Week on Monday after posting maybe the best two-game performance of anyone in the league this year.

Eight days ago, he scored a career-high 33 points in a home win against Stanford. For an encore, he scored 24 in a win against first-place Cal. On the weekend, he made 19 of 29 field goals. Despite his torrid week, Aden remained in his spot as the Cougars' sixth man on Thursday night.

Aden had come off the bench in every game since the end of November, after missing three-straight contests with a concussion.

Still, Aden was second on the team with 15.1 points per game, just behind Motum's 15.4.

"We count on Faisal quite a bit, especially the last couple games," Bone said. "He's a great scorer. When he's not on the floor and we don't have that extra scoring presence, it hurts."

Aden was born in Somalia but moved to San Diego as a child. He played for two high school teams in Texas before enrolling at Hillsborough Community College in Tampa, Fla.

There, he averaged 20.4 points as a freshman and 23 as a sophomore. The Cougars recruited him from a junior college camp after thinking Klay Thompson might elect to leave school early, which he did.

How the Cougars fill his role - and how long they must fill it, perhaps the entire season - will shape the rest of the year.

"We can have someone step up score 10, have another guy with five assists or something like that," said guard DaVonte Lacy. "We're not going to step up and replace him by one person.

"We need to replace him as a team effort."