SAN DIEGO (AP) — Arizona opened the NCAA tournament with a victory, exactly what a No. 1 seed is supposed to do.

The way it happened, with that jittery start and ease-off-the-gas-pedal finish, the Wildcats will likely hear those upset picks even more now.

Anxious early and a bit too comfortable late, top-seeded Arizona pulled out a 69-59 win over Weber State in the West Regional on Friday, a victory that's unlikely to change predictions that the Wildcats will lose in the next round.

"We are fortunate to advance and I know the next game will be a terrific game," Arizona coach Sean Miller said. "One of my hopes is, (having) one of these under our belts, we will be more ourselves and better on Sunday."

The first full day of the NCAA tournament was a wild one filled with upsets, and the bracket-busting trend continued early Friday, when Mercer, a No. 14 seed, knocked off mighty Duke.

Arizona (31-4) appeared to be next in line, falling into an 8-point hole in the opening 6 minutes.

Arizona closed in around Weber State (19-12), shutting down the Wildcats during two big first-half runs, seemingly putting the fairytale to bed.

Instead of running away, the Wildcats backed off, allowing Weber State to trim a 21-point lead down to nine in the closing minutes.

Arizona pulled out the victory, but it was merely solid, not great, particularly since the next game — against Gonzaga or Oklahoma State on Sunday — is the spot the Wildcats have been picked to go down.

Nick Johnson had 18 points, Aaron Gordon added 16 and Arizona blocked 11 shots while holding Weber State to 30 percent from the floor.

"We won and have to get ready for the next game," said guard Gabe York, who hit a pair of 3-pointers to jump-start Arizona out of its first-half funk. "The thrill of winning, moving on to the next round is what we play for."

Weber State put up a fight in its first NCAA tournament appearance since 2007, clearly not intimidated by Arizona and its cast of future NBA players.

The Wildcats jumped on Arizona early and clawed back when they could have folded, at least making the Wildcats uncomfortable before losing steam.

Davion Berry scored 24 points, Joel Bolomboy has 11 points and 16 rebounds, and Richaud Gittens added 12 points while triggering Weber State's second-half comeback.

"We came in expecting to win, trying to win," Weber State coach Randy Rahe said. "The guys did a tremendous job. I thought we could have pulled in the tents and our guys got a little more tough and showed resilience like they have all year."

Arizona had been in this spot before, facing a quick-trigger 3-point shooting team in the opening round.

A year ago, Belmont was a popular bracket buster pick against the Wildcats because of its ability to shoot the 3, but Arizona turned the slight into motivation and ran over the Bruins.

Even after an opening day of upsets in the bracket, there were no calls for one against Arizona this year.

But just as Mercer was busy taking down Duke, Weber State gave the 16-over-a-1-seed miracle a glimpse of life, holding Arizona without a field for nearly 5 minutes during a game-opening 10-2 run.

The dream popped with a flurry of blocked shots, steals and runouts the other direction.

After falling into the early hole, one of the nation's best defenses flexed its muscles against the Big Sky-champion Wildcats, jumping into passing lanes, swatting shots, turning nearly every possession into a fight against the shot clock.

Weber State missed 12 of 13 shots as Arizona went on two big runs and shot 6 of 24 in the first half with nine turnovers that Arizona turned into 12 points.

"They are a great defensive team as we know," Weber State senior guard Jordan Richardson said. "We just had to get good shots and didn't."

The desert Wildcats shook off their early offensive funk with an array of dunks and 3-pointers, racing past Weber State with runs of 14-2 and 13-3 to go up 32-20 at halftime.

Arizona looked as if it was going to run away with it early in the second half, only to watch Weber State scratch a huge lead to under double digits with 4 1-2 minutes left.

Arizona turned back every attempt Weber State made after that to pull out the victory, but will likely face more upset predictions for the third round after this one.

"We know we'll need to play better in the next round," Miller said.