TUSCON, Ariz. (AP) -- Brandon Williams had 14 points and six assists to lead a balanced Arizona attack and the Wildcats opened defense of their Pac-12 regular-season title with a 64-56 victory over Colorado on Thursday night.

Brandon Randolph had 11 points and freshman Devonaire Doutrive tied a season high with eight for the Wildcats, who were without starting guard Justin Coleman most of the way because of an undisclosed injury.

Coleman, who came in averaging 10.1 points and was second on the team with 41 assists, played four minutes in the first half and missed his only field goal attempt.

McKinley Wright IV had 17 points and six rebounds and Lucas Siewert had 11 points for the Buffaloes (9-4, 0-1), who have lost three of their last four. Tyler Bey had 11 rebounds.

Arizona (10-4, 1-0) did not lead for the first nine minutes before rallying. Williams had seven points and Doutrive had six as the Wildcats closed the first half on a 26-13 run for a 39-24 halftime lead and never again trailed.

Colorado trimmed a 17-point deficit to 57-50 on D'Shawn Schwartz's 3-pointer with 2:47 remaining before Randolph hit a layup to halt the rally.

Chase Jeter had seven points, eight rebounds and two blocks for Arizona, which is an NCAA Division I-best 90-4 at home since the start of the 2013-14 season.

Colorado had not played since Dec. 25 and Arizona had not played since Dec. 22. The rust seemed to show at the offensive end as Colorado shot 35.8 percent with 17 turnovers and Arizona shot 43.1 percent.

Arizona's Ira Lee had five points and three rebounds in 13 minutes. He spent Dec. 23 in jail after pleading guilty to driving under the influence last summer.

 Notes:

• Sophomore guard Brandon Randolph finished with 11 points Thursday, and has scored in double figures in all 14 games this season. He's one of three Pac-12 players to have scored in double figures in each of his team's games.
• Arizona has now won nine straight Pac-12 openers under coach Sean Miller. The Wildcats improved to 9-1 in Pac-12 home openers under Miller.
• The Wildcats are 90-4 at home since the start of the 2013-14 season, which is the best mark in the country.
• Freshman guard Brandon Williams finished with 14 points and six assists in Thursday's win. It's the fourth time this season Williams has had at least six assists in a game. He has 43 assists to nine turnovers in nine home games this season.
• The Wildcats had five players score at least seven points in Thursday's win.
• Freshman Devonaire Doutrive played a career-high 12 minutes Thursday. He tied his career high with eight points, and established a new career high with four rebounds.
• Sophomore forward Emmanuel Akot tied his career high with seven points.
• Miller improved to 15-5 against Colorado with the win. He is 7-0 against the Buffaloes in Tucson.

Quotes:
"The first 20 minutes of this game was among our best basketball of the year. We moved the ball really well against the zone. We played good defense and good offense. Without Justin Coleman at the forefront of it, it made us feel really good going into the half. But with the type of team that we have, we have a hard time putting two halves together. Colorado deserves some credit, but we had some plays that were headscratchers throughout the second 20 minutes. We went from playing our best or among our best ball in the first half to playing some of our worst in the second. But I was just happy to hold on, win, talk about it, learn from it and move on to Utah on Saturday." – Sean Miller
 
"As we've watched him grow in practice, from the onset I thought that there could be a period in time when he would be valuable to our team because his style is different than everyone else. He's an offensive rebounder and he's a tremendous athlete. He had a couple of turnovers, but that's to be expected when you're a young player and you haven't played earlier. But he's clever. He understands when to pass, when not to. I was excited to see it because that's how things are supposed to go, where a young guy fights, scratches and claws his way into the lineup and doesn't give up on himself." – Miller on Devonaire Doutrive.
 
"I've seen a lot. You guys don't really see it, but we see it every day in practice. He does the same thing that he did with those offensive boards. He's long. He has a 6'9" wingspan, so he can play defense and get in the gaps. As you guys could see in the Red and Blue (scrimmage), he was very active. We needed that tonight, and he showed up." – Brandon Williams on teammate Devonaire Doutrive.