BOSTON — Isaiah Thomas scored 13 of his 33 points in the fourth quarter and the surging Boston Celtics held on to beat the Philadelphia 76ers 116-108 on Wednesday night.

It was the 40th straight 20-point game for Thomas, tying the team record set by John Havlicek during the 1971-72 season. Marcus Smart added 21 points and eight steals for the Celtics.

Boston has won four in a row and 11 of 12. Philadelphia’s loss ended its three-game winning streak.

The Celtics won despite committing a season-high 24 turnovers, though they needed a late run to preserve the victory.

Dario Saric led the 76ers with 20 points and 11 rebounds. Robert Covington added 18 points but left late in the fourth quarter after crashing into the Boston bench while diving for a loose ball.

Boston won the first two games of the season series by a combined five points. Wednesday’s meeting was nearly as tight, with 10 ties and 11 lead changes.

The Celtics were a little erratic on offense to begin the game, turning the ball over five times in less than four minutes and 12 times in all during the first half.

Philadelphia took advantage, scoring 21 points off Boston turnovers in the opening 24 minutes.

It was tied at 61 at halftime, but Boston used a 12-2 run at the start of the third quarter to create some breathing room. Philadelphia didn’t go away, and took its first lead of the second half on Nerlens Noel’s dunk with just under eight minutes to play.

Then it was Thomas time.

After struggling in the second and third quarters, he scored nine straight Celtics points to put them back in front 101-99 with 5:42 left.

Noel tied it with a pair of free throws following a flagrant foul on Al Horford. But then Boston surged again, scoring seven straight as part of a 13-2 run.