MILWAUKEE -- It wasn't easy, but the Boston Celtics extended their winning streak to three games, holding off the Milwaukee Bucks down the stretch for a 112-108 overtime victory Saturday night at the Bradley Center.

Playing the second half of a back-to-back and for the fourth time in four nights, Isaiah Thomas scored 37 points and Jae Crowder added 20 more for the Celtics, who shot 41 percent for the game but knocked down 14 3-pointers.

Thomas himself accounted for six of those while Crowder added four more. But Crowder did his most important work of the night from the free-throw line, connecting on four attempts in the final 30 seconds to put Milwaukee away.

"Coming here without Al and without Avery, I thought we played pretty darn well, to be honest," Boston coach Brad Stevens said. "Defensively, in overtime, I thought we were excellent."

Thomas has scored 20 points or more in his last 31 consecutive games.

"He was good," Stevens said. "He was really good. He got to the rim. They really collapse so you have to kick it out. His ability to get to the rim started others' ability to get to the rim and we were able to get enough kick outs and finishes to win."

Milwaukee got 21 points from Giannis Antetokounmpo and 17 from reserve Michael Beasley. But Jabari Parker started 0-for-8 from the floor and went 2-for-13 from the game to finish with four points while the Bucks shot 42.5 percent.

"Teams get a lead on us," said Bucks center Greg Monroe, who finished with 14 points and 13 rebounds. "We do a great job of continuing to fight and get back into the game, but those lapses early in the game cost us. Sometimes that one run early in the game hurts you."

Milwaukee trailed by 11 at the half but Thon Maker, making just his second career start, used a dunk and layup on consecutive possessions to cut the deficit to five with 7:53 left in the quarter, part of an 11-0 Milwaukee run.

But while Boston went 7-for-21 from the floor, Thomas scored six in the quarter and went into the fourth holding an 81-73 lead.

The Bucks stormed back and cut the deficit to one when Monroe fed Antetokounmpo for a reverse layup to make it 88-87 with 7:31 remaining.

Antetokounmpo's 3-pointer tied the game at 90 with 6:30 to play and a three-point play from Greg Monroe with 4:54 left gave Milwaukee a 95-94 lead -- its first of the game.

"We had that lead way too early for them not to go on a run so you expect it," Stevens said. "You just have to keep your composure and management."

The Celtics responded with five straight but Milwaukee tied it up again at 102 when Monroe hit one of two free throws with 36 seconds remaining in regulation. Both teams had chances to win it in the closing seconds, but couldn't cash in.

After Boston scored the first six points of overtime, back-to-back 3-pointers by Snell tied things up at 108 with 1:13 left.

He got one more chance, with 45 seconds to go, but came up short and Milwaukee for the seventh time in its last eight games.

"(Playing) a back-to-back against one of the best teams in the East, we had our opportunities," Kidd said. "We just couldn't capitalize on them tonight.

"They never quit. they gave everything they had tonight. It would have been easy to let go of the rope, especially there in the overtime being down, but those guys fought to the end. When you do that, good things will happen."

NOTES: Boston C Al Horford was expected to return Saturday night after sitting out Friday with a strained groin, but instead did not travel to Milwaukee and sat out a second straight game. The Celtics were also without G Avery Bradley, who missed his sixth straight game with a sore right Achilles. ... Bucks rookie F Thon Maker was in the starting lineup for the second time in his career Saturday. Maker scored a career-high eight points in eight minutes Friday night at Toronto. "We would like to see more (from Maker), so somebody has got to sit and we're going to start him tonight," Bucks coach Jason Kidd said before the game. ... The Bucks and Celtics were meeting for the first time this season. Boston won the season series a year ago, taking three of the four games, but the teams split their previous six meetings in Milwaukee.