Rudy Gay and Tyler Hansbrough both scored 17 points to lead the Toronto Raptors to a 97-89 preseason victory over Boston on Monday night in Celtics' coach Brad Stevens' NBA debut.
DeMar DeRozan had 13 points and Terrence Ross added 12 for the Raptors.
Gerald Wallace led the Celtics with 16 points, and Jared Sullinger had 14 with six rebounds.
The 36-year-old Stevens was hired in July after a successful run at Butler University.
The Celtics had seven new players, mainly due to a blockbuster deal that sent likely future Hall of Famers Paul Pierce and Kevin Garnett to the Brooklyn Nets in a draft-night deal. GM Danny Ainge wanted to start rebuilding the team before the two became ineffective or retired.
Ainge also traded coach Doc Rivers to the Los Angeles Clippers for a first-round draft pick during the offseason.
The Raptors also made a big trade during the offseason, sending Andrea Bargnani to the New York Knicks in early July for three players and three draft picks.
The teams will face each other in the season opener in Toronto on Oct. 30.
Boston point guard Rajon Rondo is expected to miss at least the season's first month after undergoing surgery for a torn ligament in his right knee last season.
The game was tied at 84 midway into the fourth before the Raptors pulled away with an 11-3 run.
Boston trailed 67-58 in the third, but scored 15 of the next 21 points, tying it on Wallace's basket.
The Celtics' debut under Stevens didn't get off to a good start. They missed their first seven shots from the field and didn't score their first point until Kris Humphries' foul-line jumper nearly 4 minutes in.
Boston had only six rebounds in the first half.
Toronto led 14-2 in the opening 7 minutes.