The University of Arizona guard Nick Johnson (13) lofts a shot from the lane over Colorado forward Dustin Thomas (13) late in the second half of their Pac-12 game at McKale Center, Thursday, January 23, 2014, Tucson, Ariz. Photo by Kelly Presnell / Arizona Daily Star

Kelly Presnell/Arizona Daily Sta

On yet another bright Arizona Wildcats evening, when Sean Miller found it “awesome” to tie another school record, there was a dark side the coach still could not ignore Thursday night.

By the time Arizona’s dazzling, defensive-oriented 18-4 start turned into a 69-57 win over Colorado at McKale Center, tying UA’s school record for consecutive wins over college teams at 19, some of the stats had evened out, including a hot-button one that is particularly close to Miller’s heart.

That is, Arizona and Colorado each had 32 rebounds, and the Buffs managed 10 offensive rebounds, just one fewer than the No. 1 Wildcats’ total.

It was the second time in the past three games that the Wildcats, so dominant on the boards for most of the season, had tied their opponent in rebounding.

Arizona, which also tied USC 30-30 on the boards in Los Angeles on Jan. 12, entered Thursday’s game out-rebounding opponents by an average of 10.6 per game.

“If you ever want to get scared as an Arizona fan, when you see us not out-rebound our opponent, that’s the sign of a lot of bad things that are coming our way,” Miller said. “Some of it was Colorado is a very good offensive rebounding team, but we have to do a better job of rebounding.”

On the surface, you could argue it wasn’t a big deal. After all, when a team goes up 18-4, maybe it’s human nature to relax a bit.

But, as good as the Wildcats have been during their school-record 19-0 start, they sometimes need rebounding to compensate for weaker areas.

On Thursday, UA made only 3 of 15 three-pointers, and hit just 57.1 percent of its free throws, needing the early scoring of Brandon Ashley, a game-high 18 points from Nick Johnson and another dunk-a-thon from Aaron Gordon (12 points) to get it done.

It was good, it was a record, but it wasn’t quite what the Wildcats were hoping for against a team that appears to still be learning how to play without all-around leader Spencer Dinwiddie, who wasn’t even on the bench Thursday because he just underwent knee surgery Monday.

So while the early lead turned into a 39-24 halftime lead, and a 20-point lead in the second half, ultimately it became a 12-point home-court win in which Miller didn’t even feel comfortable enough to use more than his top eight players.

Ideally, Johnson suggested, the Wildcats would have taken that 18-4 run and kept it going.

“I think that’s what we have to do better,” Johnson said. “We did get up 15 at half and I think they won the second half by three. Great teams do that. They keep their foot on the pedal, keep on getting stops and baskets.”

Then again, there’s also a big picture Miller and the Wildcats were looking at. They are 19-0 after all, and 6-0 in Pac-12 play, tying a school record for most consecutive wins against college teams last set when they were defending national champions during the 1997-98 season.

That year, the Wildcats whipped through their first 16 Pac-10 games unbeaten, looked to a showdown in the regular-season finale at UCLA — and lost to USC in overtime before they faced the Bruins.

UA also won 19 straight between Dec. 28, 1992, and Feb. 27, 1993, and, if you really want to go back, the Wildcats actually won 22 straight between the end of the 1913-14 season and the middle of the 1916-17 season. But that streak, overseen by “Pop” McKale himself, included mostly games against YMCA teams and Tucson High School.

Arizona will attempt to break the college-opponent record on Sunday against Utah.

Meanwhile, Colorado dropped to 15-5 and 4-3, but the Buffaloes will get another shot at Arizona in Boulder, Colo., on Feb. 22, when they may have figured out how to play without Dinwiddie’s presence.

In one sense, they may have started how to figure it out in the second half.

“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 of that. It’s a tough place to win.”

The Buffs came back to outscore UA 33-30 in the second half in part because forward Xavier Johnson had a season-high 21 points, 16 of which came in the second half.

But it was never nearly enough for the Buffs to get out of that 14-point hole.

Early in the game, the Wildcats held Colorado to just 1-for-9 shooting while building the lead, getting seven of their 18 points during the stretch from Ashley.

“That’s just a little glimpse of what we can do,” Gordon said.

Ashley, who finished the first half with nine points, had a three-pointer and a hook shot under the basket to help Arizona’s early offense. Ashley finished with 15 points.

Because he’s been a better outside shooter this season, teams have guarded Ashley more on the perimeter but they left him wide open in the left corner for an early three that catapulted UA’s early run.

“They definitely have been picking up on me a lot more recently,” Ashley said. “I was a little bit surprised with that shot.”

Colorado pulled within 20-14 with 9:33 left in the half but then Arizona went on another run, 12-2, and led comfortably the rest of the half.

Gordon accented it all as he knows well how to do, throwing down five dunks and a layup over the course of the game.

“It’s just another way I score,” Gordon said, smiling. “If that’s the easiest thing for me to do, that’s what I’m gonna do.”

Sportswriter for the Arizona Daily Star covering Arizona Wildcats basketball