Tuesday night’s Celtics banner-raising was a new experience for nearly every member of Boston’s roster and coaching staff.

But not for the man coaching the road team at TD Garden.

New York Knicks head coach Tom Thibodeau had a front-row seat for the Celtics’ last banner ceremony in 2009. The 66-year-old was a Boston assistant back then, serving as associate head coach under Doc Rivers.

Thibodeau shared fond memories of that night during his pregame news conference.

“I think it’s a great night for the franchise, for the city, for the fans and certainly for the team,” he said. “They’ll be known forever as a group, and I think that’s what makes it special. No one’s really going to remember who scored how many points, but they’re going to remember that that was a championship team. And obviously there’s 18 of them, so that’s pretty special.”

The Celtics now are looking to hang banners in back-to-back seasons for the first time since 1969, and Thibodeau’s Knicks will be one of their top Eastern Conference challengers. After posting the second-best record in the East, New York swung blockbuster trades for Mikal Bridges and Karl-Anthony Towns, whom Thibs and Co. hope can help vault them past the reigning champs.

Celtics head coach Joe Mazzulla knows the moves made the Knicks a more formidable opponent.

“I just looked and said they got better,” Mazzulla said pregame. “… I think it was June 28 when they made the trade (for Bridges). When you see that, you’re like, ‘Damn, your enemy’s gotten better.’ So what’re you gonna do about it?

“They made trades to get better, and we believe in the roster that we have. And it’s about us finding internal ways to get better every single day. They’re a great team. We think we are, too. It’s a great first test for us, and there will be more along the way.”