MIAMI -- Not that there was any doubt about this, but the Phoenix Suns are going to the playoffs.

The Suns didn't leave any doubt in a matchup of conference leaders, either.

Devin Booker scored 23 points, Mikal Bridges added 21 and the Suns shook off a slow start to beat the Miami Heat 111-90 on Wednesday night -- becoming the first team this season to clinch a postseason berth.

"I told the guys it was one of the best defensive performances I've ever seen," Suns coach Monty Williams said. "I've been around for a little bit."

Booker, returning from a four-game absence for virus-related issues -- he said he was asymptomatic and didn't have any problems -- flirted with a triple-double, finishing with nine assists and eight rebounds.

His first trip to the playoffs last season ended with a loss in the NBA Finals. He's looking for a bit more this time.

"We know what we're working for," Booker said.

Phoenix improved the NBA's best record to 53-13, and the reigning Western Conference champion Suns have now beaten all other 29 teams this season -- the first time they've done that since 2006-07. It's the first time the Suns are 40 games over .500 since the end of the 2006-07 season, when they finished 61-21.

The Suns also avenged a 23-point loss to Miami in January.

"I'm sure they remembered that," Heat coach Erik Spoelstra said. "They wanted to really make a statement tonight. They just outplayed us."

Coming off a victory Tuesday night at Orlando, Phoenix improved its NBA-best road mark to 25-6. The Suns have an 8½-game lead over Memphis and are nine games ahead of both Golden State and East-leading Miami.

Deandre Ayton had 19 points on 9-for-10 shooting and 10 rebounds for the Suns, who got 11 points and 15 rebounds from JaVale McGee, and 11 points apiece from Jae Crowder and Cameron Payne.

Duncan Robinson scored 22 points for Miami, which lost for just the third time in its last 15 games.

"They were first to the ball a lot," Robinson said about the Suns. "They were the aggressor. ... Unacceptable."

Bam Adebayo and Tyler Herro each scored 17 for the Heat, which played without Jimmy Butler (sinus congestion) and lost key reserve Caleb Martin midway through the second quarter to a hyperextended left knee. The Heat expect to know more Thursday.

The Suns were down by 11 early, took a two-point lead at the half and then outscored Miami 34-19 in the third quarter to blow matters open. Booker capped the quarter with a long 3-pointer, the Heat went 1-for-8 in the quarter from beyond the arc and it was 91-74 going into the final 12 minutes.

"He was ready," Bridges said about Booker's return.

Phoenix is now 13-13 when trailing by double digits this season. It's on track to become just the seventh team in the last 10 seasons to finish .500 or better in games where it trailed by double-digits. Four of the prior six made the Finals.

Miami came out flying, scoring 25 points in the first 6 minutes -- a burst fueled by five 3-pointers. The Heat were 9-for-12 from the floor in that stretch, 5-for-6 from 3-point range and finished the burst by making seven consecutive shots.

That's when Phoenix's defense showed up. The Heat were 5-for-27 on 3s the rest of the way. An 18-7 run by the Suns pushed the margin to 80-65 late in the third and the lead eventually swelled to 27 in the fourth.

"We wanted to make a statement here," Booker said.

Information from ESPN Stats & Information and The Associated Press was used in this report.