The Boston Celtics (42-21) celebrated the long-awaited return of Jayson Tatum on Friday night.

But the night also came with a new setback in the frontcourt.

Veteran center Nikola Vucevic fractured the ring finger on his right hand during Boston’s 120-100 win over the Dallas Mavericks (21-42) and is expected to miss about a month.

According to reports from ESPN’s Shams Charania, Vucevic will undergo a procedure Saturday to repair the fracture.

The injury occurred early in the first quarter. Vucevic had just entered the game when Dallas center Moussa Cisse grabbed at his hand while defending a post entry pass. Vucevic remained in briefly but exited after playing just two minutes and headed to the locker room, where the Celtics quickly ruled him out for the remainder of the night.

Luka Garza replaced him in the rotation for the rest of the game.

The timing of the injury was particularly unfortunate for Boston.

Just hours earlier, Celtics head coach Joe Mazzulla had expressed optimism about finally having a full roster available with Tatum returning from the Achilles injury that sidelined him for nearly 10 months.

“Our team is whole now,” Mazzulla told the media before tipoff.

That reality didn’t last long.

Vucevic’s absence leaves Boston once again relying heavily on its younger frontcourt options, including Neemias Queta and Garza, as the team continues its push toward the playoffs.

The 35-year-old center had been providing valuable depth since arriving in Boston at the trade deadline in a deal with the Chicago Bulls (26-37). The Celtics acquired Vucevic in exchange for Anfernee Simons and a second-round pick, while also receiving a second-rounder in return.

In 11 games with Boston entering Friday night, Vucevic had averaged 11.4 points and 7.8 rebounds in roughly 23.5 minutes per game while stretching the floor as a capable outside shooter.

Before the trade, he had been producing at a higher clip with Chicago, averaging 16.9 points and nine rebounds across 48 games while hitting 38% of his 3-point attempts.

A 15-year NBA veteran, Vucevic has built a long resume that includes stints with the 76ers (34-28), Magic (33-28) and Bulls. Over his career, the 6-foot-9 big man has averaged 17.1 points and 10.4 rebounds per game while maintaining a reliable perimeter shot for a center.

Boston was still able to secure the victory Friday night, improving to 42-21 and keeping pace near the top of the Eastern Conference standings.

But the Celtics will now have to navigate the next month without one of their most experienced frontcourt options - just as the roster had finally begun to look whole again.

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Tom Carroll is a contributor for Roundtable, with boots-on-the-ground coverage of all things Boston sports. He's a senior digital content producer for WEEI.com, and a native of Lincoln, RI.