Luka Dončić singlehandedly outscored Paul George, James Harden and Russell Westbrook.
The Celtics doubled up the Heat in the first quarter, 32-16, and led by as many as 37.
Suns GM James Jones believes Phoenix can be the first team to "maximize" Kevin Durant's talent.
After a chippy series with the physical Heat, Jayson Tatum had a strong response to those who have questioned the Celtics' toughness.