“Where the towels at, rook?”

Deandre Ayton’s eyes widened, realizing he had dropped the ball on his postgame chore as Trevor Ariza’s voice boomed through the Suns’ locker room. Ayton hit “pause” on the swarm of humans and recording devices ballooning by the second, then quickly emerged from the shower area with a stack of towels for Ariza and the rest of the Suns veterans.

“Thanks, rook!” a purposely overzealous Ariza hollered. “Way to play, boy!”

That was perhaps Ayton’s only blunder on the day he later described as a dream come true.

The NBA’s No. 1 overall draft pick dazzled in his regular-season debut, compiling 18 points, 10 rebounds and six assists against Dallas to join Alvan Adams and Shawn Marion as the only rookies in franchise history to record a double-double in their first-career game. He witnessed a fourth-quarter shooting outburst from Devin Booker that left him “in shock.” He soaked in a roaring crowd that made the “floor (feel) like it was shaking” as the Suns finished off a 121-100 victory.

“This is the most fun I’ve ever had playing basketball,” Ayton said when asked what he will most remember about the day.

Scratch that. Ayton had two mishaps Wednesday.

He went through shootaround on an empty stomach. Though he obeyed his normal 7:30 a.m. wakeup call, he was too “lazy” to make his normal breakfast of eggs, spinach, turkey bacon, fruit and milk.

Good thing the morning workout was “pretty light,” Ayton said, with more focus on the defensive details than physical exertion. He left the arena one minute before noon, unwilling to budge on his meticulous afternoon routine.

He played with his husky, Rocky, for exactly 20 minutes, verbalizing the night’s goals to his very good boy. He screamed at the television during a round of the NBA 2K video game, stopping when his Suns fell behind the computer-controlled Mavericks at halftime. He recharged with a one-hour nap. He did not take any text messages or calls.

“I can’t miss anything,” Ayton said of those game-day habits. “Superstitious, that’s how I am.”

Ayton returned to the arena in style at 5:09 p.m., wearing a custom royal blue suit made by the same New York-based designer responsible for his draft-night wardrobe. He stepped on the floor for a 12-minute shooting cycle, breaking from his calm demeanor only to let out a frustrated “Ah!” following a missed elbow jumper.

Instead, Ayton unleashed that pregame excitement back in the locker room, skipping and dancing before a 6:55 p.m. team meeting. Around the same time, Bailey Williams and Alyson Furch — two members of Ayton’s management team — sorted through about 40 game tickets in various lower-bowl sections to be dispersed to family, friends and business associates.

At 7:11 p.m., Ayton led the Suns onto the court for final warmups, occasionally looking into the crowd and nodding. He shimmied along with the music during roster introductions, but turned stoic when his name was announced third in the starting lineup.

The first opponent Ayton exchanged pre-tipoff pleasantries with was fellow rookie Luka Doncic, who apparently owes Ayton $1,000 for losing a summer ping pong game. Jitters bubbled up when the 7-foot-1 Ayton met the equally imposing DeAndre Jordan at midcourt for the jump ball. Jordan also delivered an early “wakeup call” to Ayton, planting a forearm into Ayton as he tried to move in from the top of the key to crash the glass.

“I just found myself on my butt,” Ayton said. “I’m like, ‘Wow, OK. This is really it.’ It was like a self-check. I’m like, ‘OK, this is a grown man’s league.’”

Ayton corralled the Suns’ first rebound and scored his team’s first points, bullying the smaller Doncic for an And-1 layup in the opening minute. Then he sank two jumpers in a row, igniting the Suns’ terrific offensive performance in which they shot 54.3 percent from the field, drilled 19 3-pointers and dished out 35 assists.

“Everything felt like it was in rhythm,” Ayton said. “It felt like AAU.”

Clinging to a diminishing fourth-quarter lead, Ariza pulled Ayton aside to remind the rookie that grabbing crunch-time rebounds is “how you be great.” Ayton snatched four in those final minutes and consistently rolled hard to the basket after setting a pick, helping set up Booker’s 19-point explosion in the period. Ayton watched Booker embracing his big moment and electric atmosphere, another reminder of why Ayton takes the team’s “Time to Rise” theme to heart and wants to “bring hope to Phoenix.”

With 23.3 seconds to play, Ayton took a lob from Booker for an easy dunk to cap the Suns scoring. He secured one final rebound less than 12 seconds later. As the clock ticked down, Ayton locked eyes with his mother, Andrea, sitting courtside and acknowledged, “I’m tired.”

The postgame flurry — the live ESPN interview, the hovering microphones, the towel duty — is why Ayton was the last man to leave the Phoenix locker room.

Coach Igor Kokoskov greeted “the big fella” with a congratulatory handshake in the hallway. Ayton signed autographs for a persistent group of kids. He stopped for a brief chat with player-turned-broadcaster Eddie House. He bent down to wrap his family and friends in hugs.

At 11:09 p.m., Ayton stepped into the arena’s attached parking garage, ready to return home. An ice bath and more NBA 2K — maybe he’d finish off the Mavericks in the virtual world this time — awaited him.

“First game,” Ayton said. “One of many. … I’m super happy. We’re gonna have a lot of fun.”

(Photo of Deandre Ayton by Mark J. Rebilas / USA Today Sports)