Bobby Portis made a putback off Giannis Antetokounmpo's missed free throw with 15 seconds left, Jrue Holiday snuffed Marcus Smart on Boston's final two possessions and the Milwaukee Bucks beat the Celtics 110-107 on Wednesday night to take a 3-2 series lead.
Antetokounmpo had 40 points and 11 rebounds, Holiday finished with 24 points, eight rebounds and eight assists and Portis added 14 points and 15 rebounds for the defending NBA champion Bucks.
Milwaukee has a chance to wrap up the Eastern Conference semifinal in Game 6 at home Friday night. The Celtics need a win to force a decisive seventh game back in Boston on Sunday.
The Celtics led by 14 in the fourth quarter before the Bucks closed the gap, tying it at 105 on Holiday's 3-pointer with 43 seconds left. Jayson Tatum, who scored 34 points in all, hit a pair of free throws to give Boston the lead.
Antetokounmpo went to the the line with a chance to tie it and made the first, then Portis grabbed the rebound of the second and put it in off the backboard to give Milwaukee its first lead since early in the second quarter.
Smart drove to the basket but Holiday blocked him and came away with the ball, throwing it off Smart while falling out of bounds. Pat Connaughton made a pair of free throws with six seconds left, then Holiday stole the ball from Smart on his desperation dash for a potential game-tying 3-pointer.
The have Bucks won two of the three games in Boston to swipe home-court advantage.
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Antetokounmpo had his best shooting game of the series, going 16 for 27, but he also committed seven turnovers.
Jaylen Brown scored 26 points for Boston, 16 of them in the third — and 12 of those in the last four minutes of the quarter, when Boston turned a 71-68 edge into a 12-point lead.
The Bucks scored nine of the game's first 11 points, but Boston closed the gap midway through the quarter. The Celtics ran off 11 straight points early in the second, capped by a Marcus Smart steal, tossed ahead to Brown for an alley-oop to Tatum that brought the crowd to its feet.
But the Bucks scored 17 of the next 24 points to make it 58-55 with nine minutes left in third.
The Celtics were without big man Robert Williams III for the second straight game — and the fourth time this postseason — because of left knee soreness. He had been listed as questionable before being ruled out pregame.
Milwaukee remained without Khris Middleton, who has done some on-court work as he attempts to come back from a sprained left knee. He has not played since April 20 in Game 2 of the first-round series against the Bulls.
"He's done a little bit on the court and we're feeling good about where he is and optimistic," Bucks coach Mike Budenholzer said. "But it's kind of the same update it's been for the last handful of days."
Milwaukee guard George Hill (abdominal soreness) did play.
Tacko Fall, the 7-foot-6 former Celtic, took in the game from the front row, under the basket. Massachusetts Gov. Charlie Baker and New England Patriots owner Robert Kraft were also at the game. … The Celtics only had two turnovers in the first half, to nine for the Bucks. … Celtics subs Daniel Theis and Derrick White made their first nine shots.