BOSTON — Isaiah Thomas scored 19 of his 44 points in the final quarter to lift the Boston Celtics over the Toronto Raptors 109-104 on Wednesday night in a showdown for first place in the Atlantic Division.

It was the fifth straight win for Boston, which moved 1 ½ games ahead of the Raptors in the division and holds the Eastern Conference’s No. 2 seed.

Jae Crowder scored 14 points for the Celtics and Al Horford had 11. Thomas had 18 of Boston’s final 23 points.

Kyle Lowry led Toronto with 32 points, former Celtic Jared Sullinger had 13 and Norman Powell added 12. The Raptors have lost seven of nine.

In a final quarter that rivaled playoff intensity, Celtics forward Jaylen Brown was fouled on a breakaway attempt and walked over and had words with Lowry — before a few others player joined in and had to be separated by the officials. Boston’s Terry Rozier and the Raptors’ DeMarre Carroll were each given a technical foul.

With the Celtics trailing by eight, Thomas scored nine straight points to give them their first lead of the game — 95-94 on a driving basket with 4:39 to play.

The lead changed hands six times over the next 3 ½ minutes — with Thomas’ 3-pointer from the left wing giving Boston a 103-101 edge with 48.1 seconds left.

Toronto led by 11 at the halftime and scored 13 of the first 19 points in the third, pulling to a 75-57 edge on Lowry’s 3-pointer from the right corner.

TIP-INS

Raptors: G DeMar DeRozan was out for the fifth time in six games with a right ankle injury.

Celtics: G Avery Bradley missed his eighth straight game with a right Achilles tendon injury. Coach Brad Stevens said he’s practiced the last two days, but the team wants “to make sure that when we get him back, he’s back on the court and limit the chance that it’ll happen again.” … F Kelly Olynyk was out with a strained left shoulder.

IMPRESSED

Stevens talked about the play of Lowry before the game, admiring both the overall guard play in the league and that of Toronto’s star.

“There are so many guards right now that can make exceptional plays off the dribble,” he said. “Maybe more so and a higher efficiency than I’ve seen before, and Lowry’s one of the best of them.”

NICE ENDING

Thomas hit a 36-foot 3-pointer with 2.5 seconds left to cap off his 16-point first quarter.

UP NEXT

Raptors: At Orlando on Friday in the second of three straight on the road. They’ve split two meetings against the Magic this season.

Celtics: Host the Los Angeles Lakers on Friday night in the first meeting this season between the longtime rivals.