Maybe the only thing that can slow these Arizona Wildcats down are injuries and suspensions.

Opposing defenses aren’t working.

No. 3 Arizona beat the UMBC Retrievers 103-78 on Sunday in McKale Center, surpassing the 100-point mark for the second time in as many games this season.

Continuing to play at a torrid pace, the Wildcats shot 61 percent from the field, 53.6 percent (15-28) from 3 and 10-14 from the line.

“If you like scoring, you saw it here today," head coach Sean Miller said.

After scoring 32 points against NAU in the season-opener, Allonzo Trier led the way with 30 points Sunday, becoming the eighth player in Arizona history to score 30 or more points in consecutive games.

The junior guard was 10-18 from the field, 5-12 from 3, and 5-7 from the free throw line.

Deandre Ayton posted his second double-double with 19 points (9-13 FG) and 13 rebounds, and threw down two thunderous dunks (more on that later).

Arizona pushed the ball early and often, averaging 15 seconds per possession, a substantial difference from the 18.7 mark they posted last season, showing a new willingness to take shots early in the shot clock.

Arizona had 25 fastbreak points, and six different Wildcats sank two or more 3s.

“Coach wants us to play fast,” said UA point guard Parker Jackson-Cartwright said. “On makes and misses we try to get out and not shoot fast and take bad shots, but getting up fast and getting a good shot.”

Jackson-Cartwright had nine points (3-5 3PT) and nine assists. Alex Barcello added eight points (2-4 3PT), six assists, and five rebounds in 17 minutes (no turnovers, either).

Arizona had 25 assists and 13 turnovers as a team.

“There’s so many weapons on the wings and in the post, I just try to get the ball out as fast as I can and find people,” Jackson-Cartwright said.

After a shaky defensive performance in the first half, Arizona only led 56-47 at the break despite shooting 70 percent in the first 20 minutes.

A 3-pointer from Jourdan Grant cut Arizona's lead to 58-55 with 17:48 left in the second half, but that’s as close as the Retrievers would get.

Arizona outscored scored UMBC 47-31 in the second half, holding the Retrievers to a 31.3 field goal percentage, while the UA offense never stopped clicking — even when UMBC went to zone.

“They ran a lot of good action, they switched defenses and they kept us honest all night and made it tough on us,” Jackson-Cartwright said of UMBC. “We just tried to withstand their runs and we did that."

Ira Lee had a career-high 10 points and three rebounds in 15 minutes. Emmanuel Akot and Dylan Smith each hit a pair of 3s, finishing with six points a piece.

Smith, who was suspended for the season-opener, also had two blocks, using his length to swat two 3-pointers in his UA debut.

Like Arizona, UMBC had incredible success hitting 3s, shooting 14-28 from distance. Jairus Lyles, the America East’s returning leading scorer, had a game-high 31 points on 21 shots.

“He made a lot of tough 3s. He’s shifty, he can shoot the long ball, and he’s strong to the rim,” Jackson-Cartwright said. “He’s tough to deal with.”

Lyles scored 23 points in the first half, helping UMBC get off to a hot start.

UMBC hit its first four shots of the game, including three 3s, to take an early 11-5 lead. Arizona would counter with a 14-0 run, but neither team slowed down offensively.

The Wildcats shot 9-14 from 3 in the first half, while the Retrievers shot 8-14.

Arizona led by as much as 16 after a Smith 3 with 9:46 left in the half, but the Retrievers closed to the gap to 41-35 after Lyles banked in a desperation 3 with 6:04 left.

Trier had 15 points on 10 shots in the first half, Ayton had 11 points and six rebounds on seven shots.

Keanu Pinder returned from suspension and had four points, four rebounds, and a monstrous block in 12 minutes.

Arizona returns to action Thursday when it will host Cal State Bakersfield at 8 p.m. MST.

Miller said Arizona can improve on “everything” before its trip to the Bahamas later in the month. Considering how dominant the Wildcats have already looked, that’s a scary thought for any team that has to stand in their way.

“Our gift this year is as much on offense as it is on defense,” Miller said. “It’s up to us to work on a few things that I know we can control better defensively and continue to take advantage of the gifts we have offensively."

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Deandre Ayton posterizes a poor defender

Ayton put his 43.5-inch vertical on display when he caught a back door lob from Barcello and slammed it in the face of a helpless UMBC defender midway through the first half.

“I was running down the court with my mouth open,” Jackson-Cartwright said. “I couldn’t believe it.”

That’s one way to beat a zone.

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Randolph returns

Brandon Randolph made his debut after missing Friday’s opener with a concussion, but the freshman was limited to four minutes off the bench.

He sank a 3 with under two minutes in the second half for his first points, then scored on a layup in transition on a feed from Barcello.

Randolph missed nine days, seven of which he was unable to do anything on the court, Miller said.

Randolph was cleared to practice Saturday, but the Wildcats didn’t have a full-contact practice that day.

“So to put him out there in five-on-five game like that, I don’t know if it would be smart for him or our team,” Miller said.

“I was just glad he could get in the game and now he can start working his way back. Obviously we have depth and we have to take advantage of it. Sometimes guys have to sacrifice and there’s no question on this team that there’s going to be some sacrificing involved for us to emerge and be the team we want to be.”

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Final stats

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Follow Ryan Kelapire on Twitter at @RKelapire