TUCSON, Ariz. -- The Arizona Wildcats' season is in the home stretch. Allonzo Trier's is just getting started.
In his 10th game back from suspension, Trier scored a season-high 25 points, including four 3-pointers, and No. 4 Arizona beat USC 90-77 on Thursday night to stay alone atop the Pac-12 and set up a Saturday showdown against No. 5 UCLA.
Trier missed the first 19 games of the season for testing positive for a banned substance. He's been trying to catch up since.
"Every game allows me to get more comfortable," he said. "This late in the season you start hitting your peak and playing your best basketball and I'm kind of still really early compared to everybody else."
His shooting eye sure seems to be back.
In his first 10 games back, Trier made 10 of 33 from 3-point range. He was 4 for 6 Thursday night and is 8 for 11 in his last two games.
"Allonzo is a really, really improved 3-point shooter," Arizona coach Sean Miller said. "It's just his path this year, missing 19 games and coming back. It's taking him a little bit of time to really show how much better of a 3-point shooter he is, but he did a really good job out there."
Rawle Alkins added 12 points and Lauri Markkanen had 11 for the Wildcats (26-3, 15-1) in Arizona's 21st consecutive home win.
Bennie Boatwright scored 23 points and Chimezie Metu had 15 for the Trojans (22-7, 8-7), who lost their third in a row -- to the top three teams in the conference (Arizona, Oregon and UCLA).
The Wildcats closed the first half with a 12-2 run and were up by as many as 16 points in the second half.
Arizona made 11 3-pointers in 20 attempts, its most 3s in a Pac-12 game this season.
After shooting under 30 percent for the first 10 minutes of the game, the Wildcats got the offense rolling and finished at 53 percent from the field against the Trojans' zone defense.
It's a defense that gave Arizona problems earlier this season.
"We were that team that everybody threw the zone up," Miller said, "and I hope that teams do that now because we are able to get quality 3s. We have really five or six players who are capable of shooting a good percent from 3."
Parker Jackson-Cartwright made 3 of 4 3s against the Trojans, Alkins 2 of 2 and Kobi Simmons 2 of 4.
USC shot 51 percent but 3-pointers and turnovers were the difference. Arizona had 23 points off the Trojans' 14 turnovers to USC's nine points off eight turnovers.
"We played well enough offensively," Trojans coach Andy Enfield said, "but we could not stop them in the second half. They had it rolling on offense."
The Wildcats, down by as many as nine points early, finished the first half on the 12-2 run, all of the points coming on 3-pointers -- two by Simmons and two by Trier.
After the Trojans cut the lead to 51-41, Arizona outscored USC 20-6 over a 4-minute span to go up 71-55 on Dusan Ristic's inside basket with 9:36 to play. Another 7-1 spurt, punctuated by Jackson-Cartwright's 3, gave Arizona a 78-62 lead with 5:03 left.
Trier said it will take a better effort to beat UCLA.
"We have to play better defense in order to compete with them," he said. "They're the best offensive team in the country and we have to match that with our defense. It will be a challenge. It's something I'm looking forward to and it should be a great game."
The Wildcats will try to finish the season 15-0 at home in their showdown with UCLA on Saturday night.
Overall, they have won 21 in a row at McKale Center dating to last season's home loss to Oregon. That was the only loss at home for Arizona in 71 games.
With another sellout crowd, attendance at McKale topped 9 million since the building was built in 1973.
Arizona took care of the required business without looking ahead to the Bruins. Now comes a UCLA team that Arizona beat in Los Angeles earlier this season.
The Wildcats host No. 5 UCLA in a major Pac-12 showdown on Saturday night.