BOSTON -- Isaiah Thomas took off for the basket, just what the Boston Celtics needed with the game tightening up.

Thomas had consecutive key baskets and finished with 21 points, Evan Turner scored 19 and the Celtics won their fourth straight with a 100-91 victory over the New York Knicks on Sunday night.

With the Celtics clinging to a 90-85 lead and just over three minutes to play, Thomas came up with his timely driving baskets to push the lead back to nine. The first came on a drive down the lane and the second he easily beat everyone down the floor after grabbing the rebound.

"Super quick because he loves to score," Turner said of Thomas. "He was tenacious and I think he knew we needed a couple of plays and stepped up."

The Celtics had opened an 88-78 lead on Turner's driving basket with 6:11 to play before New York made its charge. Thomas' plays made sure the Celtics were never in danger of losing.

"We need him to be a good playmaker for us," Boston coach Brad Stevens said. "I think he would tell you it wasn't his best day, but again, he did make the biggest plays to push the lead from five to nine. That gives you a little bit of a comfort level."

Thomas added eight rebounds and six assists.

Jae Crowder defended Knicks star Carmelo Anthony tough and scored 18 points, and Kelly Olynyk added 11 points and nine rebounds for Boston.

"He's tough. I mean, he's tough," Anthony said of the 5-foot-9 Thomas. "Little guy with big heart out there. Hard to stay in front of him, got to stay in front of him. Draws a lot of attention. If he don't have it with the way that they space the court, when guys (are) making shots, it's kind of tough to kind of stop him."

Anthony led the Knicks with 29 points despite shooting just 11 of 26. Kristaps Porzingis had 16 points and 12 rebounds.

New York, which shot just 37.1 percent, lost its fourth straight. The Knicks committed 13 turnovers.

"Turnovers always swing the momentum, especially on the road," New York coach Derek Fisher said. "That's where we really got ourselves in trouble."

Boston pushed its 10-point halftime lead to 59-44 on Crowder's 3-pointer from the left wing 4:11 into the third quarter. The Celtics led 77-65 after three quarters.

Thomas made a behind-the-back pass to Jonas Jerebko, who nailed a 3 from the right wing to cap an 18-6 run that gave Boston a 47-33 edge late in the first half.

The Celtics led 51-41 at halftime.

LOOKING FOR HELP

Anthony said the Knicks never felt comfortable shooting the ball.

"It's more stress than anything because you're praying (for them) to go in, you're hoping them to go in," he said. "It's not confident when you're shooting the ball."

ANOTHER DOUBLE-DOUBLE, ROOKIE

Porzingis had his 12th double-double of the season. New York took him with the fourth pick in the 2015 draft.

TIP-INS

Knicks: Porzingis walked to the bench gingerly after taking a charge, but came back. He had X-rays that were negative on a right finger injury in Saturday's loss in Atlanta. ... Before the game, Fisher agreed with Anthony, who recently said the players needed to want to win more. "For sure," Fisher said. "The players are the ones that have to make the plays. We can create game plans, strategies, coverages, etcetera, but when the game starts it's really those guys that have to get it done."

Celtics: G Marcus Smart returned and played 13 minutes after missing the previous 18 games with a lower left leg injury. Stevens felt the schedule didn't allow for much 5-on-5 play in practice, so the 6-foot-4 guard needed to get in shape through game action. "He's going to have to impact the team the best way that he can by defending and by being tough and by being an energy player for the time being," Stevens said.

UP NEXT:

Knicks: Host Detroit on Tuesday.

Celtics: Host the Los Angeles Lakers on Wednesday.