Senior guard Mark Lyons, in particular, was better than Belmont. He scored 23 points, including 14 in the second half, as the sixth-seeded Wildcats rolled past the undersized Bruins.
Arizona shot 57 percent and outrebunded Belmont 44-18.
"I guess the stat that is overwhelming when you look at it is our rebounding," Arizona coach Sean Miller said. "I think that shows the effort level that we played with."
Truth be told, Arizona dominated all the way around while improving to 26-7.
According to Byrd, the Wildcats who showed up for their first game in the West Regional were much more impressive than the ones who went 5-5 over the final 10 games heading into the tournament.
"I was more impressed with the team I saw tonight than I was in scouting them," Byrd said. "I thought they were more engaged and more focused. If they keep playing that way, they can beat a lot of people."
Arizona jumped to a 14-4 lead in the opening eight minutes. The Bruins made only one of their first 12 field-goal attempts and appeared to be on the ropes.
"I don't think it was nerves," said Belmont's Ian Clark, who finished with 21 points. "We've always talked about coming out and starting being ready, being mentally focused. ... I just don't think the shots were early."
The Bruins rallied, however, when Kerron Johnson's 3-pointer triggered a quick 10-2 run that got them back in the game.
It was 21-18 with 4 minutes, 16 seconds left in the half before Arizona reasserted itself. The Wildcats ended up with a 32-20 lead at halftime.
"You just don't want to be that far down," Byrd said.
Arizona's defense played a pivotal role in the dominating half, limiting the Bruins to 7-of-27 shooting.
"This is just cryin' over spilt milk," Byrd said. "But we missed five layups. And we missed the same kind of 3s they made throughout the game. If you're going to beat a team that is that good and that talented, you have to make it go the other way."
Arizona kept rolling in the second half.
Lyons hit a 3-pointer on the Wildcats' first possession, and the Wildcats' lead eventually ballooned to 64-43 with 8:17 left.
Belmont got as close as 11 with just more than five minutes remaining, but Kevin Parrom's layup and a 3-pointer by Solomon Hill slammed the door.
"I'm proud of these guys," Miller said. "They did a great job, and we're excited to be playing Saturday."
Johnson finished with 22 points to lead Belmont, which finished its season with a 26-7 record after winning the Ohio Valley regular-season and tournament championship. NCAA Tournament live blog
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