The Celtics fought back from an 18-point deficit to lead heading into the final three minutes, before a strong finish from the defending NBA champions.
The power forward told reporters: "It's difficult doing what we do, but that's why we're the champs, to do the difficult thing again and get the job done. Tonight was a good start. We just have to build off of it."
Bosh scored 16 points during the 93-86 win.