Tatum's shoulder made clean contact with James' jaw, which sent LeBron to the locker room late in the second quarter with a strained neck.
"I felt like I needed to go back to the locker room, which I did, and kind of recalibrate," James said after the loss, per ESPN.com's Dave McMenamin. "It was a tough blow. Obviously incidental. His shoulder hit me right square in my jaw. Just wanted to go back to the back and make sure everything was fine. But I don't think it—it didn't affect my game after that.
However, Cavaliers head coach Tyronn Lue noted that James didn't look quite the same after returning from his huddle with the team's medical staff.
"It was a tough collision," he said, per McMenamin. "Knocked his head sideways. Of course he came back, but when he came back, I don't think he had the same punch that he had before he left as far as attacking the basket, playing with that force and power we talked about at shootaround. We'll see how he feels."
James finished Game 2 with 42 points, 12 assists and 10 rebounds for his third triple-double of the postseason.
He'll have three days to rest up before the Celtics and Cavaliers clash Saturday in Game 3 of the Eastern Conference Finals at Quicken Loans Arena.