Marcus Smart’s return to TD Garden is certain to be emotional on Sunday, and even though the former Celtics guard won’t play due to a finger injury, Joe Mazzulla is still hoping he can make one of his old signature plays.

“Hopefully during a timeout, I don’t know if his hand still hurts, but he can dive on the floor for a loose ball and roll one out,” the Celtics coach said.

That’s obviously unlucky as Smart, now with the Grizzlies, continues to recover from the right finger injury he suffered last month. But Smart will be in the building on Sunday, and his presence will evoke emotions and happy memories of one of the most beloved players in recent Celtics history. A tribute video is expected and the reception will be special.

After nine seasons with the Celtics that included endless hustle plays and iconic moments that endeared himself to the city, a Defensive Player of the Year award, an NBA Finals berth and all of the charity and community work that made him a fixture in Boston, Smart was shockingly traded to the Grizzlies just before midnight on June 21 in a deal that landed Kristaps Porzingis in Boston.

Marcus Smart blindsided by trade from Celtics: ‘It was definitely shocking’

The emotions were raw. His Celtics teammates shared in the shock. Payton Pritchard said Saturday it was “wild to see.” Brad Stevens – while making the move that signaled the Celtics’ trust in Derrick White as their starting point guard – said it was hard to do because of how much Smart meant to the organization and city.

Smart expressed some disappointment. In the wake of the trade, he said that the Celtics had told him the week before they had no plans to trade him. He said he was blindsided by the news. He was asleep, and his agent called his fiance, who woke him to tell him. But that didn’t take away his love from the city he grew up and became an adored figure in. And even though it was time for the Celtics to move on from him, he was irreplaceable in many ways.

“I’ve always said you don’t replace a guy like him, you just find different ways to be able to do it,” Mazzulla said. “So who he is will forever be etched into the city of Boston because of what he’s done in community service, and what he’s done here, just helping represent – I think he’s one of the guys that started our defensive foundation before I got here because it was high-level and execute different coverages. So just like I said, who he is off the court and then kind of what he brings from a mindset standpoint and a defensive intensity standpoint. It’ll be good to see him (Sunday).”

Smart’s return will be a reminder of that defensive foundation and standard of grit and toughness that he set over his nine seasons. When he was traded, Jaylen Brown made it a point to put an emphasis on defense to ensure the Celtics wouldn’t drop off on that end in Smart’s absence.

The Celtics have maintained a Top 5 defense without Smart. The addition of Jrue Holiday – another veteran All-Defensive guard – has been huge, White has maintained his All-Defensive production and Brown has played the best defense of his career.

It just looks a little different. But no one can quite do it like Smart.

“You don’t replace it, I think it just looks different,” Mazzulla said. “I think (Jayson) Tatum dove on the floor for a loose ball (on Thursday night), Derrick’s winning plays, the back tips in transition, Jrue’s constant intensity, I think just focusing on everybody’s strengths and what they’re able to do. Jaylen’s individual defense, like that’s just as tough as what another player does, it just looks different, and so I think you just have to highlight each person’s definition of toughness and how that pertains to helping our team win.”

There’s no question, though, that defensive culture the Celtics have maintained started with Smart. Sunday will be a chance, among other things, to appreciate that.

“I think when you have a guard that plays as hard as he does who guards centers, guards point guards, picks up full court, boxes out, charges, all those little things that I think go into it,” Mazzulla said, “like I think for him to win Defensive Player of the Year, he’s what, the first guard since Gary Payton, it’s only something bigs do, so when you see a guard have an impact on the game on so many levels the way he did, I think that’s kind of what started it.”