Jayson Tatum expressed immense relief after the Celtics needed overtime to defeat the Pacers in Game 1 of the Eastern Conference Finals.

Tatum scored 36 points, including 10 in overtime, after Jaylen Brown’s tying 3-pointer with 6.1 seconds remaining in regulation, leading Boston to a 133-128 victory over Indiana.

Jrue Holiday added a season-high 28 points, and Brown finished with 26, helping the Celtics hold on to home-court advantage with Game 2 set for Thursday in Boston.

“I’m so glad we won that game because I would have been sick,” Tatum said postgame, via Jay King.

Tatum acknowledged the significance of the win but remained focused on the bigger picture.

“It doesn’t prove anything. We won a big-time game. The series is far from over. … But one step at a time. This is a big-time win tonight and come back and get ready for Thursday,” he added.