Arizona's games against Colorado have been some of the most anticipated on the top-ranked Wildcats' schedule.
The teams have built an emerging rivalry in only two previous seasons since the Buffaloes joined the Pac-12, splitting six games.
Arizona, though, was never threatened Thursday night at McKale Center against the short-handed Buffaloes, leading by double digits for nearly 34 minutes in its 19th straight win.
The Wildcats won 69-57, tying their modern school record for consecutive victories. Arizona (19-0 overall, 6-0 Pac-12) equaled the mark set by the 1992-93 and 1997-98 teams.
"It's awesome," Arizona coach Sean Miller said. "Never one day has any of us walked into McKale and said, 'It's not good to be No. 1.' It's a fantastic feeling. Everyone wants to be No. 1."
The Wildcats have been ranked No. 1 for the past seven weeks.
Guard Nick Johnson scored 18 points and forward Brandon Ashley had 15 to lead Arizona. Forward Aaron Gordon added 12 points, with five of his six baskets coming on dunks. He was 1 of 7 from the field on everything else.
Forward Xavier Johnson led the Buffaloes with 21 points, hitting 4 of 5 3-point shots. Forward Josh Scott had 15 points and 11 rebounds, often working in the post against Arizona 7-foot center Kaleb Tarczewski.
Colorado, which played its third full game without star point guard Spencer Dinwiddie (ACL), already is eager for the next meeting on Feb. 22 in Boulder.
"We were playing the No. 1 team in the nation, but they weren't that good," Colorado's Johnson said. "There's no excuse for not getting the win."
Arizona made their first six shots from the field in the second half -- including two dunks by Gordon -- to build on a 15-point halftime lead. Gordon's reverse dunk in traffic gave the Wildcats a 51-31 edge.
"If that's the easiest thing for me to do," Gordon said of his dunks, "then that's what I'm going to do."
Colorado never truly threatened, although the Buffaloes did whittle the lead to 66-55 with 1:15 to go on a layup by guard Askia Booker. Nick Johnson and guard T.J. McConnell missed the front end of one-and-one free throw opportunities for Arizona after that, but Colorado failed to get any closer.
Miller didn't express concern that his team didn't totally put away Colorado, but he did not like the fact that Colorado tied Arizona with 32 rebounds. The Wildcats have not been outrebounded through 19 games.
"That's such an important strength of ours," he said. "We are going to have games that we go 3 of 15 from three. But we can't have games where teams begin to rebound with us because that's our strength."
Colorado, which dropped out of the national polls on Monday after six consecutive weeks in the Top 25, fell to 15-5 overall and 4-3 in the Pac-12. The Buffaloes have never defeated a No. 1-ranked team in 16 tries.
"We continued to battle and we didn't fall apart," Colorado coach Tad Boyle said. "The way our guys stuck together was a positive, and we have to build off that. It's a tough place to win."
Arizona, which controversially beat Colorado in overtime at McKale Center last season when officials used replay to overturn Sabatino Chen's 3-pointer at the regulation buzzer, was in control from the start.
The Wildcats scored the first nine points of the game and didn't allow Colorado to make a field goal until Booker's drive with 14:35 left in the half. Arizona was up 18-4 before the Buffaloes briefly rallied to close within 20-14.
The Wildcats answered with a 12-2 run, punctuated by a Johnson fast-break dunk, to lead 32-16 with 3:35 to go.
Colorado, without Dinwiddie, often had trouble in its half-court offense against Arizona's man-to-man defense, shooting 29.6 percent in the first half.
"When you lose your best player -- somebody I believe could play in the NBA for a long time -- you don't just all of a sudden move on and say, 'We're as good,'" Miller said. "But they have some good young players that will develop."
NOTES: Arizona freshman F Aaron Gordon and junior G Nick Johnson were among the 23 players selected Thursday for the Oscar Robertson Trophy midseason watch list as chosen by the United States Basketball Writers Association. ... Xavier Johnson's 21 points for Colorado were one off his career high, set last season against Oregon. ... Colorado F Josh Scott posted his ninth double-double of the season. ... Former Arizona F Solomon Hill, a rookie first-rounder with the Indiana Pacers, attended the game. The Pacers played in Phoenix on Wednesday night.