BOSTON – No matter what the Milwaukee Bucks did against the Boston Celtics on Monday, they couldn't change the reality of what had already happened before they took the field at TD Garden.

“We played two terrible games and there's no excuse for that,” Bucks coach Doc Rivers said after Monday's game. “But it happens. I thought we played relatively well (against the Celtics), but we couldn't sustain it tonight. But I think our guys like where we’re going.”

The Bucks kept the score close through the first two and a half quarters, but the Celtics pulled away, outscoring Milwaukee 37-26 in the third quarter. The result: a 119-108 loss for the Bucks, their third straight loss, dropping their record to 1-3.

With their win, the Celtics proved what was already clear before the game. At 4-0 this season, the defending champs are the class of the NBA and the Bucks have work to do to get to where they can attempt to challenge Boston in the postseason.

“It’s been around for years and you can’t replace it. “That’s not possible,” said Bucks star Giannis Antetokounmpo after he scored 30 points, 10 rebounds, six assists and seven turnovers in Monday’s loss. “You can put together the best players, but you just have to know how to play with each other, sacrifice for each other, play the right way, know where your teammates are going to be, who's going to take over, who's in charge” – that's what winning teams do do.

“And our goal is to get there. Of course, we're not there yet at the moment, but I don't think we're far away from it. I don't care about the record. For me it’s just about continuing to build, continuing to stay healthy and getting to where we want to go.”

For the first time since the Bucks' season opener in Philadelphia, Milwaukee played with a high level of mental focus and physical intensity in the first half. That was supposed to happen every night, but it didn't happen against the Chicago Bulls or Brooklyn Nets, so it was a welcome return to the baseline that was expected when the Bucks took the court. That was perhaps to be expected against the best team in the NBA, but after the last two games it wasn't guaranteed.

But while the Bucks had the effort and intensity needed early in the game to keep up with the Celtics, their performance wasn't on the same level as the defending champions. That was evident in the final three minutes of the third quarter, as the Bucks made a series of small mistakes that the Celtics took advantage of to eventually build a 15-point lead just over 90 seconds into the fourth quarter.

While the errors weren't massive, they highlighted the significant gap in execution between the two teams at this point in the 2024-25 season.

After a jumper from Bobby Portis and a technical free throw from Damian Lillard, the Bucks took an 80-79 lead with 2:42 left in the third quarter. It would be their last lead of the game as things quickly went downhill for the Bucks.

As is often the case, the Bucks positioned Portis in the left block on their next offensive ball.

While Portis has a size advantage over Jayson Tatum, he was called for a trip — one of his four turnovers in 19 minutes Monday night — and the Bucks ended up with an empty possession.

“I just thought Bobby got faster tonight,” Rivers said. “I got involved with someone and you know, he has games like that every now and then. I love him because he’s emotional, but there are nights when he can be overwhelming.”

On the other hand, the Bucks made a mistake that has happened far too often this season, and Derrick White made them pay for it.

The Bucks rank just 12th in defensive rebound rate this season, having grabbed 72.9 percent of available defensive rebounds according to Cleaning The Glass, but their team context makes it feel much worse.

With a defense focused on protecting the rim and forcing contested shots, the Bucks haven't focused on forcing turnovers. They were always very low in this category when they were consistently among the top 10 defenses under Mike Budenholzer, but they were a spectacular defensive rebounding team and so they managed to win the possession battle every night.

This year's defense, led by defensive coordinator Greg Buckner, is not expected to force turnovers, nor is Budenholzer's defensive system. However, that means the Bucks have to be an elite rebounding unit, and that hasn't been the case this season. As the numbers show, they were good, but not elite, and that will continue to be a problem until that changes.

After White's 3 on the reload, the Bucks came to the other side and went to Portis again at the post. This time he worked against White and made one of his favorite shots, a turnaround baseline jumper, but missed. Then the Bucks showed another one of their bad habits on defense.

The Bucks did what they needed to in transition by finding opponents and defending the player in front of them, but their defense wasn't quite sharp enough in half-transition. This was a constant bugbear for the Bucks, as they lacked attention to detail in their rotations as transitional possessions became half-court possessions. Here, Portis didn't have enough possession of the ball and left too much space when switching with Antetokounmpo, which the Bucks forward admitted after the game.

“I think the biggest thing is getting the defensive rebound,” Portis said of how the defense can improve. “I think we sort of cleaned that part up tonight, but the 3s, the extra 3s they're hitting, just getting to touch and closing to touch is one thing we can really focus on more, I think.”

After White's mistake, the Bucks gave up another offensive rebound. And this time it was Antetokounmpo who missed the box-out against Celtics second-year forward Jordan Walsh.

Antetokounmpo is averaging 11.8 rebounds per game, but he hasn't been perfect on the glass this season and that has been a serious flaw.

All in all, without one final mistake, the Bucks probably wouldn't have had such a bad start to the final quarter.

After the game, Rivers told reporters that his team was prepared for the late-period tendencies of Payton Pritchard, who hit some big balls in the quarters. Rivers said the team's scouting report indicated that Pritchard would always look to “break right” in those situations. That's exactly what the Bucks allowed him to do on his side-step 3 to end the third.

It was the sixth time this season the Bucks allowed their opponent to score in the final 10 seconds of the first three quarters of a game. Through four games, the Bucks' opponents have scored on their last possession 50 percent of the time. These buckets can be absolute killers and the Bucks have been giving them up at an exceptional rate so far this season.

In the end, their disastrous third-quarter finish forced the Bucks to look at Monday's positives even as they faced the reality that they had won just one of their first four games of the season.

“I don’t like moral victories, but I just thought we could be that — at least for three quarters,” Rivers said. “I thought we ran out of gas a little bit. We didn’t get a lot of help from our bench tonight, so we increased the minutes.”

The schedule doesn't get any easier for the Bucks as they finish their road trip against the Memphis Grizzlies on Thursday and then play a home game against the Cleveland Cavaliers. Still, Antetokounmpo remains confident about where this team can go this season, even if that positivity is fueled more by necessity than genuine belief.

“You have to. You don't have a choice. You have to,” Antetokounmpo said. “It's the fourth game of the season. Even if we sucked, even if we were very, very bad, it's the fourth game of the season, there you have to be optimistic.

“That’s the job we have, but at the end of the day we have a great team. I believe we will continue to play better, continue to learn from our mistakes and eventually win games.”

(Photo: Paul Rutherford / USA Today Network via Imagn Images)