No matter how disheveled the Bucks looked in the last two games and the Bulls and Nets suffered incredible losses, they would provide great resistance to the Celtics. They’re too proud not to, even though they’re at the bottom of their game in the Eastern Conference and despite missing their starter, Khris Middleton.

The Celtics rose to the challenge Monday at TD Garden, not needing elite Jayson Tatum to pull away from the Bucks in the fourth quarter. Tatum had his first erratic game of the season, missing free throws, complaining about non-calls and picking up a technical.

His teammates and coaches were also irritated with Tony Brothers and his team for most of the evening. Celtics coach Joe Mazzulla disputed a call three minutes into the game. He barked at the referees most of the night as Damian Lillard hit 18 free throws in 36 minutes.

That certainly had the makings of a frustrating loss. But the Celtics were saved by their depth and relentlessness, their ability to overcome adversity rather than succumb to it.

The catalyst was backup Payton Pritchard, who again ended a quarter with a 3-pointer after scoring 19 points in the first half to keep the Celtics close. He scored 28 points in 28 minutes in the Celtics’ 119-108 win. He made eight 3-point shots while most of his teammates struggled from beyond the arc.

He started the Celtics’ 7-0 run early in the fourth period with another three-pointer as Boston held off Lillard and Giannis Antetokounmpo to win for the fourth straight time to start the season. Milwaukee, perhaps when healthier and more coherent, is expected to challenge the Celtics in the coming months, but not now.

Lillard and Antetokounmpo need support. They combined for 63 points on 21-for-41 shooting. Her teammates scored 45 of 16 of 41 points.

“I don’t like moral victories,” Bucks coach Doc Rivers said. “But I thought we could be, at least for three quarters. I thought we ran out of energy a little bit and didn’t get much help from our bench.”

And the Celtics did. Pritchard has been brilliant since struggling in the first half. He’s gone 18-for-29 from the 3-point line in the last three games, including 8-for-12 on Monday. He has embraced his spark plug role with the freedom to shoot whenever he is open. And he has worked feverishly on his shot over the years, making him a formidable weapon off the bench.

He thrilled the crowd again with a 3-pointer in the right corner at the buzzer in the third quarter, giving the Celtics a 90-82 lead and completing an 18-7 run.

“I live for those moments when the clock runs out and there are six seconds left and I get to a point and I pull up (for the jump),” Pritchard said. “In those moments I kind of lose consciousness and just let it fly. And obviously it often works. It’s really just about the energy I have to bring into every game, especially when I come off the bench. Some nights our starters may be low on energy, so I have to be responsible for bringing them that night.”

As Pritchard went through his pregame routine, a younger fan held up a sign that read, “Payton for White Boy of the Year.” It was intended as a compliment, perhaps an extreme indication that Pritchard, at six feet tall and lacking facial hair, was an ordinary man in Boston.

“I definitely appreciate it,” Pritchard said of the support. “I think it’s because I look like an ordinary person. And I feel like I give hope to everyone as tall as me. I’m not necessarily the most athletic athlete, but with hard work you can go far and I feel like I’m a role model for that. I will never give up and keep going. You can achieve anything you set out to do in life. I’m proud to give these people hope.”

That game came a day after Pritchard’s wife, Emma, ​​posted a video of him playing 1-on-1 with a young man while walking their dog to a park near Seaport. It was a testament to Pritchard’s willingness to play with anyone, anywhere.

“I had a hat on and didn’t think anyone would really notice me, but these kids saw me from afar and screamed,” he said. “I ended up going there. It was low-key, really messing around, just playing 1-on-1 with them. They were actually pretty good, little, scrappy kids who just went for it. I definitely appreciate that and have spoken to them. I like moments like that. Felt like a kid again playing outside.

“But I came after him with a bucket.”

This moment sums up Pritchard and his love for the game and his tireless work ethic. Today he is a decisive player, a scorer per minute who plays with passion and fearlessness. A shooter by the end of the quarter who has worked his way up to scouting reports.

The Celtics weren’t at their best on Monday, but they were good enough because Pritchard was good enough.

Gary Washburn is a Globe columnist. He can be reached at [email protected]. Follow him @GwashburnGlobe.