"We got hit tonight," Irving said. "When you get hit early and they consistently hit you, they buried us, which a good team should do."
Irving started for Boston after missing the previous three games because of a bruised right quad. He scored 17 points in 22 minutes.
"I didn't feel as good as I wanted to," Irving said. "Being out for a week in any profession is tough. Hopefully next game will be better."
Reserve forward Marcus Morris also returned for Boston after sitting out two games because of a bruised left hip but the Celtics suffered their second-worst defeat of the season. Boston's only bigger loss was a 23-point defeat at Chicago on Dec. 11.
"We got our butts kicked by a really good team who physically overwhelmed us," Celtics coach Brad Stevens said. "We need to do a better job."
Boston's Al Horford shot 1 for 5 and finished with two points in 24 minutes.
Toronto won its fifth straight home game and improved to 22-4 at Air Canada Centre, the best home mark in the NBA.
"I just liked the way we came out and set tone on both ends of the court," Raptors coach Dwane Casey said.
All six of Lowry's field goals were 3-pointers. His career-high is eight, set against Charlotte on Nov. 29.
"He got going and he cooked us," Stevens said.
Lowry and Miles combined for 11 of Toronto's 17 3-pointers. Lowry made his first three 3-point attempts but no other Raptor connected from long range in the first quarter. Toronto led 22-18 after one.
"We looked slow, we looked like we weren't ready to react to their speed or their physicality," Stevens said. "I think that was probably the case the whole night."
Toronto's bench extended the lead in the second. VanVleet scored 10 points and Wright had nine as the Raptors connected on 13 of 19 field goal attempts in the quarter to take a 58-37 lead at halftime.
Toronto had a 30-15 edge in bench scoring at halftime.
"We have literally two different teams and that's a great thing to have," Lowry said.
Celtics: Irving missed the only previous meeting between the teams this season, a 95-94 Boston win on Nov. 12, because of a minor facial fracture suffered in a collision with teammate Aron Baynes. ... Boston shot just two free throws in the first half.
Raptors: Toronto is 15-3 when VanVleet scores 10 or more. ... The Raptors are 31-9 when they record 20 or more assists.
Irving said the Celtics should remember how it felt to suffer a heavy defeat to their division rivals, who they'll face twice more in the regular season.
"Keep it in the back of your mind," Irving said. "I know I will."
MY COMPLIMENTS TO THE BENCH
Before the game, Stevens praised Toronto's productive second unit. "There's not many groups I enjoy watching more," he said.
Afterward, Wright was asked whether he thought Stevens enjoyed watching the Raptors bench players perform during the game-changing second quarter.
"Probably not a lot," Wright replied.
Celtics: Visit Washington on Thursday. Boston has lost its past two road meetings with the Wizards.
Raptors: Wrap up a season-long four-game homestand against the Knicks on Thursday. Toronto has won four straight home meetings with New York.
More NBA basketball: https://apnews.com/tag/NBAbasketball
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