Deandre Ayton scored 25 points as top seeds Phoenix overpowered Luka Doncic and the Dallas Mavericks on Monday while Miami exploited the absence of Joel Embiid to rout Philadelphia in the NBA playoffs.

Doncic led the scoring with a game-high 45 points but it was not enough to stop Phoenix claiming a wire-to-wire 121-114 victory in the best-of-seven Western Conference semi-final series opener.

Ayton shot 12-of-20 from the field for Phoenix while Devin Booker added offensive thrust with 23 points, nine rebounds and eight assists.

Chris Paul chipped in with 19 points and Cameron Johnson added 17 from the bench as six Suns players posted double-digit points totals.

Phoenix had sprinted out of the blocks to lead by 10 at the end of the first quarter and surged into a 69-56 lead at the interval.

They led by as much as 21 points in the final quarter before a furious late onslaught led by Doncic saw Dallas get to within five points in the closing seconds.

The Mavs rally ultimately fell short, however, leaving Phoenix 1-0 up ahead of game two on Wednesday.

- Herro spurs Heat -

Tyler Herro scored 25 points from the bench as the Miami Heat swept aside the depleted Philadelphia 76ers 106-92 in their Eastern Conference series opener.

Herro led a balanced offensive effort as top seeds Miami pulled away after trailing at half-time to go 1-0 up in the best-of-seven semi-final series.

Five Miami players finished with double-digit points tallies as the depleted Sixers faded from contention after a gutsy first-half display that left the fourth seeds leading 51-50 at half-time.

Philadelphia's preparations were rocked on Friday after confirmation that star big man Embiid had suffered an orbital fracture and concussion in the Sixers' first-round series-clincher against Toronto on Thursday.

Embiid's presence was sorely lacking at Miami's FTX Arena on Monday as the Heat outscored the Sixers 56-41 in the second half.

"They're a very good team even without Embiid," Miami coach Erik Spoelstra said. "We just were able to get organized in the second half. We did it with a little bit more thought and discipline, and just that extra effort ignited everyone on the team."

Herro led the scoring for Miami despite starting on the bench, shooting 9-of-17 from the field including four three-pointers with seven assists.

"It's always all hands on deck with us, next man up mentality no matter what," Herro said of his contribution.

"We just had to find a way to keep the offense going and guys stepped up defensively. We just want to keep playing well and keep things going."

Bam Adebayo meanwhile had a double-double with 25 points and 12 rebounds while fit-again Jimmy Butler returned to the starting line-up from injury with 15 points, nine rebounds and three assists.

Tobias Harris led the Philadelphia scorers with 27 points, while Tyrese Maxey added 19 and James Harden 16.

Sixers coach Doc Rivers lamented his team's inability to stem the flow of Miami shots. The Sixers were outrebounded 47-37, which enabled Miami to uncork 13 more shots.

"We're working with a small margin for error, so we can't give a team 13 extra shots on the road without Joel and think we're going to win a game," Rivers said.

Game two in the series takes place in Miami on Wednesday.