BOSTON — Again.

Isaiah Thomas flashed his fourth-quarter magic one more time, leading his Boston Celtics from behind to their fifth straight victory, a 109-104 decision over the Toronto Raptors on Wednesday night.

Boston’s little big man scored 18 of his 44 points in the final 6:12 (19 in the quarter), including a go-ahead 3-pointer with 48.1 seconds remaining as the Celtics completed a comeback from an 18-point third-quarter deficit for the win.

The win, over a Toronto team playing the second half of a back-to-back without injured All-Star starter DeMar DeRozan, gave the Celtics a game and a half lead over Toronto atop the Atlantic Division. It also gave coach Brad Stevens the same lead over counterpart Dwane Casey in the chase to coach the Eastern Conference All-Stars.

The team ahead at the end of play Sunday’s sends its coach to New Orleans.

Thomas, leading the NBA in fourth-quarter scoring at 10.3 points per game coming in, then hit four free throws in the final 10.6 seconds left to ice it. He also had seven assists and four rebounds. The first two of those foul shots came after a big offensive rebound by Marcus Smart.

Patrick Patterson hit a 3-pointer with 3.9 seconds left

Thomas, who scored nine straight points in 1:33 to wipe out an eight-point deficit, won a fourth-quarter shootout with fellow All-Star Dwight Lowry. The Toronto guard had 12 of his 32 in the fourth for his fourth straight 30-point game.

Thomas hit four field goals, on seven shots, in the first half, but his 10-for-11 from the foul line gave him his 33 straight 20-point games — as he closes in on John Havlicek’s club record of 40 (November, 1971-January, ’72).

In the last 12 home games, Thomas has 440 points in 433 minutes.

Jae Crowder added 14 points and eight rebounds, Al Horford 11 points and six assists and Smart 10 points, five rebounds and five assists off the bench for the Celtics, who won without the injured Avery Bradley and Kelly Olynyk.

Former Celtic Jared Sullinger, making his TD Garden return, had a season-high 13 points and six rebounds in 15:37 off the bench. Norman Powell had 12 points and Patrick Patterson and Lucas Nogueira 10 apiece off the bench.

Toronto big man Jonas Valanciunas, limited to 11:47 because of foul trouble, had just three points and three rebounds.

The Raptors, losing for the first time in three games to Boston but falling to 8-10 since the start of January, went just 14-for-25 from the foul line.

NOTES: Both teams were missing starting guards, with DeMar DeRozan out for the fifth time in the last six Toronto games with an ankle sprain. Boston’s Avery Bradley missed his eighth straight with an Achilles tendon strain and is now considered day-to-day. … F Kelly Olynyk (shoulder) was also out for Boston. … Toronto F Jared Sullinger, a former Celtic, made his first return to TD Garden. … The Raptors are at Orlando and Brooklyn Friday and Sunday, while the Celtics host the two Los Angeles teams, the Lakers on Friday and Clippers on Sunday.