The Celtics guard registered 17 points in the final eight minutes of regulation and then rallied in extra time, either making or assisting on every basket to see out the 123-116 win.
He finished with 11 assists and was backed up by Jayson Tatum, who added 21 points and seven rebounds, as the Raptors slumped to their third loss in a row after opening the season 12-1.
In New Orleans, Anthony Davis reached the same feat of a season-best 43 points as the Pelicans beat the New York Knicks 129-124.
Down 11 points in the fourth quarter, Julius Randle, who made 19 points and 11 rebounds in total, grabbed a put-back of a Davis free-throw miss to put the Pelicans 124-121 up with little over a minute remaining.
Jrue Holiday added three with 35 seconds left on the clock to seal the result, finishing with 24 points and 10 rebounds.
Jimmy Butler made his first home outing for the Philadelphia 76ers, scoring 28 points in their 113-107 victory over the Utah Jazz.
The 76ers jumped to a 16-point lead in the first quarter and kept up the momentum with 16 points from JJ Redick and 10 for Ben Simmons.
The Brooklyn Nets, meanwhile, claimed their first win in Washington in nearly four years, Spencer Dinwiddie reaching a season-best 25 points in the 115-104 victory over the Wizards.
Andrew Wiggins scored 23 points as the Minnesota Timberwolves overcame the Portland Trail Blazers 112-96.
Elsewhere, the Milwaukee Bucks fought back from 22 points down to beat the Chicago Bulls 123-104, the Memphis Grizzlies beat the Sacramento Kings 112-104 and Tyreke Evans finished with a season-high 23 points in the Indiana Pacers' 99-91 victory over the Miami Heat.