How did the Bucks come back from 14 down to beat the Celtics? Bobby Portis, big moments, and ‘a little bit of everything.’

Milwaukee center Bobby Portis (9) pulls down a key offensive rebound and puts it back up to give the Bucks a 108-107 lead.Barry Chin/Globe Staff

Growing up, Bucks forward Bobby Portis’s mother advised him to be a garbage man.

But she wasn’t talking about taking out the actual trash. Instead, she encouraged her son to clean up the misses of his teammates on the basketball court. Portis, an Arkansas native, called himself a jack of all trades as a youngster, someone who could do “everything good but nothing great.” He knew the chances of a play getting drawn up specifically for him were slim, so he heeded the advice of his mother.

“If you want scoring opportunities when you’re not getting the ball passed to you, you’re going to get the ball on the offensive glass,” he said.

Now, in his seventh NBA season, Portis channeled that same role. With his team trailing by one and 14.2 seconds remaining Wednesday night at TD Garden, Portis snagged a critical offensive board after Giannis Antetokounmpo missed his second of two free throws. Portis immediately went back up with the ball, and his putback spiraled in to give the Bucks a 108-107 lead, their first since early in the second quarter.

The sequence served as one of the final highlights in Milwaukee’s comeback effort, as the Bucks overcame a double-digit, fourth-quarter deficit to steal a 110-107 victory and 3-2 series lead in their best-of-seven Eastern Conference semifinal series against the Celtics. After the game, Portis immediately FaceTimed his mother.

“Shoutout to my mom on that,” he said. “I was in the right place at the right time.”

“He has a nose for the ball,” added Bucks coach Mike Budenholzer. “He has a nose for scoring. It’s a huge play. He just keeps coming.”

Portis finished the night with 14 points, making just 4 of his 14 field goal attempts in 28 minutes off the bench. In the fourth quarter, prior to his crucial putback, he had missed all three of his shots, including a driving layup and follow-up tip shot with just over a minute remaining.

“Some guys might be frustrated after the previous play, but Bobby just keeps coming,” Budenholzer said. “He’s able to make a huge, huge play on the offensive board putback. He’s just a competitive guy. He brings a huge fire to our team.”

Portis brushed off his poor statistical night, saying the playoffs are more about moments.

“Everybody had a moment tonight,” he said. “It’s good the Bucks came out on top.”

As the Celtics walk glumly to their bench, Bobby Portis is mobbed by teammates after delivering Wednesday's game winner.Jim Davis/Globe Staff

Through the first three quarters Wednesday night, however, the positive moments for Bucks not named Giannis Antetokounmpo were few and far between. Antetokounmpo had accounted for 32 of Milwaukee’s 77 points at that point, and was one of just two Bucks to reach double-digit scoring. He had made 13 of his 21 baskets (61.9 percent), while his teammates had connected on just 17 of 50 (34 percent).

The Bucks were down nine points headed into the final 15 minutes. And after the opening two minutes of the fourth quarter, the deficit grew to 14.

But over the course of the next four minutes, the other Bucks finally stepped up. Pat Connaughton swished two threes, Jrue Holiday made a three, Portis grabbed an offensive rebound and made two free throws, Wesley Matthews knocked down a three, and the Bucks were suddenly within four.

“Everybody contributed,” Budenholzer said. “It takes a little bit of everything to flip a 13 to 14-point game. We have to try to not put ourselves in that position.”

The Bucks have asked a lot of Antetokounmpo, especially in the absence of forward Khris Middleton (knee sprain), and he’s certainly delivered throughout the series. He can only do so much, though, and looked absolutely gassed in the final moments of Game 4.

Game 5 seemed headed toward a similar fate. It was clear Antetokounmpo would need to play all 12 minutes in the fourth quarter for the Bucks to have a chance. But Antetokounmpo’s teammates finally eased the burden.

After Portis scored to give Milwaukee a one-point lead, Holiday blocked Marcus Smart’s shot attempt as he drove down the baseline. Connaughton then knocked down two clutch free throws to give the Bucks a three-point lead, and Holiday came up big once again to pick off Smart, preventing the Celtics from even getting off a final shot attempt.

Headed into Wednesday, the Celtics were 47-4, with 31 straight wins, when leading by double-digits in the fourth quarter.

Milwaukee's Jrue Holiday delivered a key steal against Marcus Smart late in the fourth Wednesday night to seal the win for the Bucks.Jim Davis/Globe Staff

“It’s a big win,” Holiday said. “That was the plan. The plan was to come here and get a win, no matter if we were up 20 or if we were down 20. We wanted to leave here with a win.”

For the Bucks, Wednesday’s win exemplified their character and other traits that Budenholzer says are hard to quantify. For Portis, it’s representative of his role on this team.

“It’s all about patience,” Portis said. “It’s all about being connected and being a cohesive unit and sticking together. I think we did a great job of that.”