With revenge firmly on their minds, the Boston Celtics came out all guns blazing in game one of their Eastern Conference Finals rematch with the Cleveland Cavaliers on Sunday.After going on an incredible 17-0 run in the first quarter, they never allowed the Cavs to get within single digits for the rest of the game as they romped to a 108-83 win.The Cavaliers beat the C's in five games at the same stage last season and it was clear from the opening tip that the home team was determined to avenge that loss.They played with a real sense of purpose, fuelled by big performances from Jaylen Brown, Al Horford and Marcus Morris.Brown led them in scoring with 23 points, Horford added 20 and Morris posted a double-double of 21 points and 10 rebounds.

They became the first Celtics trio to score 20+ points each in a conference finals game since Kevin Garnett, Paul Pierce and Rajon Rondo did it in 2012, per NBA.com/Stats.

As a team, Boston also did a great job of shutting down LeBron James as he shot just 5-of-16 from the field for 15 points and committed a playoff-high seven turnovers.

But despite this near-perfect performance, head coach Brad Stevens believes they'll have to be even better to win game two on Tuesday night.

"I think we're very alert to the fact that we'll get a heavyweight punch (in Game 2) on Tuesday night," Stevens told reporters after the win. "We're going to have to play better on Tuesday."

With these comments, Stevens is certainly expecting to see a much better version of LeBron as it'll be difficult to see him having another off night.

With the four-time MVP playing badly, it was no surprise to see the rest of his teammates struggling too.

Kevin Love was their leading scorer on the night with 17 points but he was just 5-of-17 from the floor.

The Cavs shot 4-of-26 from three-point range and missed their first 14 shots from beyond the arc. For a team that relies so heavily on shots from deep, their inability to knock them down hurt them badly.

Many of those attempts, however, were uncontested and coach Stevens expects his team to improve in that aspect.

"According to Brad, we can get a lot better," Celtics guard Terry Rozier said about their defence, according to Boston.com's Nicole Yang.

With Boston landing the first knockout punch, it'll be interesting to see if Cleveland can bounce back in game two.

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