Jayson Tatum never doubted himself after a poor Game 3 performance, returning to a starring role as the Boston Celtics dominated the Miami Heat 102-82 in Game 4.

The Celtics had their backs to the wall in the latest tussle of the Eastern Conference Finals, with the threat of heading back to Miami for Game 5 trailing 3-1, but they made sure it was not a nervous night for the Boston faithful.

Derrick White – returning to the starting line-up after the birth of his son – started in place of the injured Marcus Smart and scored the first seven points, kick-starting a 26-4 run to open the game.

The Celtics defense proved to be immense, holding the visitors to just 42 points with less than three minutes remaining in the third quarter.

Eleven first-quarter points also set a new record for the Heat's worst offensive first quarter in any playoff game in their history.

After only scoring 10 points in Game 3, Tatum responded in fine fashion, racking up a team-high 31 points on eight-of-16 shooting, hitting 14-of-16 free throws, while adding eight rebounds, five assists and two blocks.

Speaking later, Tatum highlighted the confidence he has in his ability, despite how dark things can get immediately following a painful loss.

"Right after it's tough," he said. "You're frustrated with how you played, knowing how important this time of year is, and feeling like you let your team-mates down.

"But I think I do a really good job of sleeping it off – regardless of if I have 10 points or 46 points – the next day is the next day, and whatever happened, happened.

"Obviously I was ready to get back to playing, but I didn't doubt myself – I know how to play basketball.

"Regardless of how many points I score, [it's about] just trying to come out and help us get a win. That's most important."

With the series now tied at 2-2, Tatum called it "a new series", but he stressed his side need to bring the same intensity after a win, as opposed to just after crushing losses.

"It's 2-2 – it's kind of like a new series, a best-of-three," Tatum said.

"Human nature plays a part in [the swings in the series]. When you win a game, you can relax a little bit, but obviously when we lose a game, we feel like the next game is do-or-die, and then we come out and play how we did.

"We need to have that mindset going into Game 5 – it is a must-win game – and tonight was essentially something like that. Everybody knew it, we could all feel it, and I think it showed with the way we came out."

When asked if he enjoyed sitting out the fourth quarter after clocking 117 minutes across the first three games of the series, Tatum said: "It was extremely nice – especially because we were winning."

Celtics coach Ime Udoka made sure to highlight the efforts of White after he finished with 13 points, eight rebounds, six assists and three steals.

"He checks so many boxes for us, it's not only things that show up on the stat sheet," Udoka said.

"He's the guy that moves the ball very well, defends extremely well, multiple positions… I couldn't be more happy with him being here, and what he brings to this team."

Udoka touched on what it will take to come out on top in this series, echoing Tatum's sentiments about bringing the same intensity after a win.

"Our mindset was right coming out, we came out with the right physicality and focus," he said. "We've just got to muster that same energy when we're coming off a win, as well as a loss.

"It wasn't our best offensive night, but defensively, obviously we were elite tonight, for the most part.

"We've got room to grow still, that's the thing with us, and we can always rely on our defense. We've won several games doing that this year when our shots aren't falling.

"To hold them in the 30s for basically three quarters, it's high-level defense.

"We can do that even if our shots are not falling, it's mainly about taking care of the ball, not letting them get anything easy, and kind of wearing on them mentally."

After Game 5 in Miami, Game 6 will head back to Boston, with a potential Game 7 to be played in Miami, if required.