Al Horford's career-best playoff haul of 30 points drew acclaim as the Boston Celtics secured Game 4 with a superb fourth quarter in a 116-108 road win over the Milwaukee Bucks.

The 35-year-old veteran and five-time NBA All-Star delivered 11-of-14 shooting with eight rebounds and three assists as Boston levelled the NBA Eastern Conference semi-final series at 2-2.

Horford rose to the occasion after a third-quarter dunk from Giannis Antetokounmpo left him smarting, and steered the visitors to a crucial win at the Fiserv Forum in Wisconsin.

The center returned the favour on his opponent in the final act, with both handed technical fouls, but it was the sheer energy of the Dominican that captured the attention.

"That was a hell of a play," team-mate Jayson Tatum said. "Especially anytime Al turns back the clock and he looks like his old self, it gets everybody off the bench.

"Al plays with so much passion. When Al is playing with passion like that, everybody else has to follow."

Marcus Smart also hailed Horford, in particular for his dunk, adding: "It's a big-time play in a big-time moment.

"It's a physical game. We were on the other end a couple of times, so it felt kind of good to have that one."

Horford himself admitted the Celtics were driven to victory by a desire to close out the game after the Bucks held on for a 103-101 win on Saturday in Game 3.

"We felt that at the end of Game 3 that we were in a position to win the game, and we didn't," he added. "I was just really locked in.

"I understood the moment and what we needed to do as a group. Just come out and we were gonna do whatever it took tonight. It was one of those types of nights."

The two sides return to Massachusetts now, and will contest Game 5 at the TD Garden on Wednesday.