BOSTON -- Celtics fans roared with delight when Giannis Antetokounmpo bumped Marcus Morris, causing a referee to blow his whistle. Just four minutes into the third quarter Monday night, Antetokounmpo had picked up his fourth foul. Khris Middleton followed shortly after, crashing into Kyrie Irving.

In came George Hill and Pat Connaughton to replace the Milwaukee Bucks' two All-Stars. Two minutes later, Eric Bledsoe, who also had four fouls, checked out and took his place next to Antetokounmpo and Middleton on the bench.

The crowd inside TD Garden, where Milwaukee lost to Boston four times in the playoffs last season, was deafening. Marcus Smart, Boston's emotional leader, was back. The Celtics, trailing 2-1 in this best-of-seven series, were desperate.

"If we're honest, you see Giannis and Khris go to the bench, you're concerned," Bucks coach Mike Budenholzer said.

All of this, all at once, left the Bucks facing the one question that had hung over them all season long: When Antetokounmpo, the likely MVP, has been neutralized, can the Bucks survive?

Then the Bucks proceeded to answer that question affirmatively -- and in the most emphatic way possible. With Milwaukee stars sitting with foul trouble, the Bucks -- led by Hill -- went on a 17-7 run to end the third quarter. They gained a lead they would never relinquish and went on to beat the Celtics 113-101. The Bucks now lead the Eastern Conference semifinal 3-1.

"Some nights, the starters might not have it going," Connaughton said. "The effort and the energy when we check into the game. That's something George, me, everybody on the bench prides ourselves in. That is the 'Bench Mob.'"

To understand the significance of that run, one must understand that third quarters have been big this series. The third quarters have been so big, they've dictated who wins every game. The Celtics outscored the Bucks by 15 points in Game 1. The Celtics won that game. Milwaukee outscored Boston by 21 in the third quarter of Game 2 and went on to win. The Bucks bested the Celtics by nine points in the third quarter in Game 3. Who won that game? The Bucks.

But all of that was with Antetokounmpo or Middleton playing at least eight minutes. On Monday, they sat watching. The Bucks have maintained all season long that their depth is a key factor, but the timing was not ideal.

"Whoever we have on the floor, it's not like, 'Oh, damn, we're stuck with these guys,'" Lopez said.

When Bledsoe sat in the third quarter of Game 4, the Celtics led by two. Hill scored 9 of his 15 points in the third. Not only did the Bucks guards find ways to score, they limited Irving to just five points -- all from the free throw line.

From the bench, Middleton leaned over to Malcolm Brogdon and said, "This is a great spot to be in."

"I mean we are on the road and playing in a hostile environment," Middleton said after the game, recalling the conversation. "Most of our starters are in foul trouble and we're still in this game. It's still a winnable game."

Budenholzer said he contemplated bringing Antetokounmpo and Middleton back earlier to end the third quarter. Instead, because the bench was building the Bucks' lead, he sat them for longer. At the end of the quarter, the Bucks led 80-72.

It isn't the first game in the series that Milwaukee has leaned on its bench. In Game 3, the Bucks got a heavy offensive boost from Connaughton and Hill. Hill scored 21 points in that game, helping the Bucks to get offensive rhythm on a night when Bledsoe struggled to make shots. Connaughton had 14 points.

"They've been the difference-maker in this series," Antetokounmpo said. "It's great to have guys who can step up like that from the bench."

For the Celtics to win this series now, they would have to beat the Bucks in three straight games. Milwaukee has not lost three consecutive games this season.