BOSTON — Luka Garza and Xavier Tillman already have a nickname, given to them by Celtics wing Sam Hauser. They’ve been dubbed “the buffaloes” just because when they’re going up against each other on one of the Auerbach Center baskets, that’s what they look like battling in the post.

Garza and Tillman have a unique relationship dating back years since they’re the same high school class. Garza and Tillman also had some epic battles in the Big Ten before they both transitioned to the NBA. Now Celtics teammates, they’re still competing during practices, though they’re also expected to produce this season.

“It’s always been fun to go against him and the level of intensity he brings,” Garza said. “And he’s just one of the nicest guys, too. That’s what’s awesome about Xavier, so it’s been cool to kind of be on his team now. I hated playing against him in college, so it’s good to be on his side.”

Tillman’s been with the Celtics for the past 1.5 seasons, helping them win the 2024 NBA championship. He was acquired via trade from the Grizzlies at the 2024 trade deadline and has been with the team since then. Garza is one of the many new faces on Boston’s roster, signing with the team as a free agent as he smelled opportunity.

Both were celebrated college players, too. Garza was a two-time All-American and two-time Big Ten Player of the Year as he excelled at Iowa. He went on to be the 52nd pick in the 2021 draft, jumping around with the Pistons and Wolves before landing in Boston. Tillman broke out at Michigan State his junior year, being named the conference defensive player of the year in 2020. He left college early, selected 35th overall in the 2020 draft by the Grizzlies.

“We get together on the hoop over there every day, we work out for 20-to-40 minutes, and we just compete,” Tillman said. “And it’s nice because we were in college together, kind of going and battling one another, trying to push each other to be great. Now that we’re together and Year 5 for him and Year 6 for me, it’s pretty dope to see that we lasted the test of time and just continue to get better year in and year out.”

Tillman and Garza are two important parts of the Celtics’ front-court rotation, alongside Neemias Queta and perhaps some Chris Boucher. No position saw more change this summer for the C’s than up front; Kristaps Porzingis, Al Horford and Luke Kornet are all on different teams.

So, opportunity awaits for someone to soak up those minutes. Tillman battled knee issues last season, but he’s feeling healthy and ready to contribute. Garza has looked to get consistent playing time — Boston looks to be the best shot of his career.

“It’s been an experience,” Garza said of his journey. “It’s been a lot of ups and downs. It definitely tested me mentally, especially with my confidence. Coming in, I had such a high, almost, and then getting humbled right away. I think it was good for me, good for my career and good for me as a human being to kind of go through that.”