The defending champion Bucks were short-handed, but Dennis Schröder saved the Celtics from a disaster

Less than an hour before the Celtics faced the Bucks on Friday it was announced that Milwaukee superstar Giannis Antetokounmpo would sit out because of a sprained ankle. Celtics coaches found out before the players did, and they were slightly reluctant to even share the news.

The Bucks were already without starters Khris Middleton and Brook Lopez. Yes, these are the defending champions, but this group barely resembled that one.

“The first message was, ‘Don’t let it be an inclination to let down naturally when a guy’s missing,’” Celtics coach Ime Udoka said. “The other guys are going to play hard. They’re going to come with a nothing-to-lose attitude.”

The Celtics’ intensity level seemed low for much of the night, and as the game rumbled on and the Bucks lingered, yet another confounding home loss seemed possible.

But with Jaylen Brown out and Jayson Tatum scuffling, Dennis Schröder saved Boston. The point guard erupted for a season-high 38 points, helping his team escape with a 122-113 overtime victory at TD Garden. It was Boston’s fourth overtime game this season, and although it was hardly an inspiring performance, it did help the team get back to .500.

Tatum added 27 points on 10-for-25 shooting and Marcus Smart scored 19 points, but Schröder’s performance was most essential. The veteran signed a one-year, $5.9 million deal with the Celtics last summer, mostly because of the lack of the more lucrative offers that he was seeking.

So this year he is trying to prove his worth, and this performance was a solid statement. When he stepped to the free-throw line late in overtime, he was serenaded with ‘MVP’ chants that were certainly spliced with some humor, but also accurate for this one night.

Schröder chuckled and brushed off the attention, and after this win lamented his turnover issues — he has 14 in his last two games. But he said he is still finding his way.

“My teammates are doing a great job telling me just to go, don’t think about nothing, just play,” Schröder said. “Coaches as well, front office as well. I feel very confident right now, comfortable, and looking forward to whatever comes next.”

Udoka said that in the first half the Celtics were too focused on hunting mismatches and it hurt their rhythm. Boston had 10 first-half turnovers and trailed by 4 at the break. But a strong third quarter by Marcus Smart appeared to put Boston in control, as it pushed ahead, 92-83, early in the fourth.

Then the Bucks clawed back. A Grayson Allen 3-pointer from the left corner pulled Milwaukee within 106-103 with 1:31 remaining before a George Hill putback made it a 1-point game. After Schröder scored inside, Allen hit another 3, this one from the left arc, tying the score at 108 with 13.6 seconds left.

“We gave up two late threes where we didn’t need to gamble,” Udoka said. “We got a little greedy there.”

Boston had a chance to win at the end of regulation. Bobby Portis switched onto Tatum on the perimeter, a favorable matchup for the All-Star forward, and he created a good look as he sliced into the paint, but the 12-footer was short.

Schröder started overtime by connecting on a runner. And with Boston leading, 112-111, Portis switched onto Schröder. Aware of the point guard’s ability to get to the rim, Portis stayed back just a bit and Schröder drilled a 22-footer.

The situation repeated itself on the following possession, and this time Schröder blitzed past Portis for a layup that gave Boston a 116-111 lead with 1:31 left.

“We emphasized that before the game,” Schröder said, “to try to play pick-and-roll with Bobby Portis in it and then try to play out of it. And then just me being aggressive in overtime, it worked out. Just trying to pick my spots, and tonight they went in.”

The Celtics are now 2-2 in overtime this season, including two games that went to double overtime. The extra wear-and-tear this early in the season certainly is not ideal, particularly in this case, with Brown out and a road game against the Cavaliers looming Saturday night.

When Tatum was asked about that matchup Friday, he responded by asking if Tacko Fall would be playing. Fall spent two years with the Celtics as a two-way contract player and became a fan favorite in Boston before signing a two-way deal with Cleveland last summer.

“We’ve got to stop Tacko,” Tatum quipped. “That’s the game plan. You know how tall he is and how big he is.”

Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him @adamhimmelsbach.