The Boston Celtics are not dead and buried despite going 2-0 down to the Miami Heat in the Eastern Conference finals on Friday, insists star forward Jayson Tatum.

Four-time All-Star Tatum posted team-high figures of 34 points, 13 rebounds and eight assists as the Celtics started Game 2 strongly at TD Garden, but it was not enough.

Jimmy Butler's 27 points helped the Heat rally to claim a 111-105 victory, with a game-ending 24-9 run from the visitors leaving the Celtics facing an uphill task to seal consecutive NBA Finals appearances.

Boston now approach back-to-back road games requiring a win to keep the series alive, but Tatum retains confidence in their ability to turn things around.

"It's tough. It's a challenge," Tatum said after Friday's loss. "They came in and won two games. They played well, you have to give them credit. 

"But we're not dead or anything. We've got a great opportunity. 

"I still have the utmost confidence. Everybody has the utmost confidence. We've just got to get ready for Game 3."

Grant Williams attracted criticism for his part in the Heat's fightback, after Butler said a heated fourth-quarter exchange with the Celtics forward provided him with additional motivation late on.

Addressing the incident, Williams said: "I think he said something and I just responded. I'm a competitor and I'm going to battle. 

"He got the best of me tonight, and at the end of the day it's out of respect, because I'm not going to run away from it. 

"You either come back before you die or you come back and get a win, and I'm not willing to die in this finals. I'm ready to get a win. 

"I'm ready to come back and come into Game 3 with a better mentality, and I know this team is as well.

"We have a real, real decision to make, are we going to come back and really set the tone for the rest of this year and really make a statement? 

"Or are we going to come out and lay down? I don't think this team is built for laying down."

Miami's Kaseya Center will play host to Games 3 and 4 on Sunday and Tuesday respectively, with the Heat needing just two further wins to avenge last year's 4-3 Conference Finals defeat to Boston.