Celtics head coach Joe Mazzulla addressed reporters following Boston’s 121-113 Game 4 loss to the Knicks, a defeat that left his team trailing 3-1 in the Eastern Conference semifinals and facing uncertainty around Jayson Tatum’s health.

Tatum, who had 42 points before suffering a right leg injury late in the fourth quarter, was carried off the court with 2:58 remaining.

Speaking postgame, Mazzulla said, “No, not yet. I know it’s a lower body injury. He’s gonna get an MRI tomorrow. He’s with the doctors now.”

When asked whether any testing was conducted immediately at the arena, the coach added, “I didn’t ask him. I just got the update from him. I just asked him how he was doing.”

Mazzulla acknowledged the concern surrounding the All-NBA forward’s condition and emphasized that the team is preparing for both his status update and a must-win Game 5.

“Obviously, always concerned about someone’s health,” he said. “It’s twofold — we’re concerned about his health, where he’s at, and then we’re concerned about what we have to do better for Game 5 when we get back to Boston.”

Pressed for specifics, Mazzulla said the medical staff informed him only that it was a lower body injury and confirmed no details regarding whether it involved Tatum’s ankle or Achilles.

“The fact that he had to be carried off — like you said, he’s the type of guy that gets right up, so he didn’t,” Mazzulla noted. “It’s tough to watch a guy like him get carried off like that.”

Mazzulla confirmed he had not yet spoken directly with Tatum and described the locker room’s mood as focused but reflective following the home team’s second-half surge.

“Tonight, we just didn’t play well defensively, and we’re in a hole,” he said. “Knicks played great tonight… especially in that third quarter with their pace, their offensive execution.”

New York outscored Boston 37-23 in the third quarter and gained control behind Jalen Brunson’s 39 points and 12 assists.

Mazzulla pointed to rebounding and transition defense as pivotal issues: “Obviously, Brunson’s a great player and Bridges separated it with their scoring… they beat us on the boards.”

Boston will now attempt to stave off elimination at TD Garden, where the Knicks won the first two games of the series.

Despite the deficit, Mazzulla expressed confidence in his group’s resolve: “They’ll be ready. That’s just who they are… you trust the character of the guys in moments like this.”