Cleveland, OH (SportsNetwork.com) - Kyrie Irving swished a 3-pointer at the halftime buzzer and held out his arms, extending three fingers from each hand.

With all the noise made about LeBron James leading the Cleveland Cavaliers back to the postseason and Kevin Love making his playoff debut, it was easy to forget about the player who had the two highest-scoring games in the NBA this season.

Irving also made his postseason debut, scoring 30 points to lead Cleveland to a 113-100 win over the Boston Celtics on Sunday in Game 1 of their first-round playoff series.

"He's our floor general," said James. "He set the tone early with his ability to shoot the ball and to get in the lane."

Irving scored 20 of his 30 points in the first half, including 12 in the second quarter when he went 4-for-4 on 3s, including the buzzer-beater to give the second-seeded Cavs a 62-54 lead after they trailed by eight.

"I thought we found him when we needed to and I thought we gave him the space he needed," first-year Cavs coach David Blatt said of Irving. "He's tough to guard, let's be honest."

Cleveland led by as much as 20 in the third quarter. James didn't sit much in the game, but he was on the bench when the Cavs scored the last nine points in the third after letting Boston get within six.

The game was never closer than 10 after that.

Cleveland hosted a playoff game for the first time since May 11, 2010, when James was booed by some fans after going 3-for-14 in a Game 5 loss to Boston in the Eastern Conference semifinals.

The Cavs were eliminated two days later. Two months after that, James went on national TV and announced he was leaving Cleveland to play for the Miami Heat, who he would lead to four consecutive Eastern Conference titles and two NBA championships, becoming the postseason star fans in his home state hoped he would be for the Cavs.

James scored 20 points in a game-high 42 minutes on Sunday and Love, after 439 regular season games with Minnesota and Cleveland, finally got a taste of the postseason and finished with 19 points and 12 rebounds.

"It makes it easier when I have guys like this who have my back and consistently give me confidence to go out there and be myself," said Irving.

Isaiah Thomas had 22 points and 10 assists off the bench to lead the seventh- seeded Celtics. Evan Turner and Kelly Olynyk added 12 points apiece and Marcus Smart, Brandon Bass and Jae Crowder each scored 10.

Boston went 24-12 after being a season-worst 14 games under .500 on Feb. 1 and reached the postseason after a one-year absence despite trading away star point guard Rajon Rondo in December to key an apparent rebuilding period.

The Cavs had too many weapons in Game 1, Celtics coach Brad Stevens said.

In addition to outrebounding Boston 46-34 and scoring 18 second-chance points off 15 offensive boards, the Central Division champs threw up 31 3-pointers, making 13, and scored 20 points off 14 Boston turnovers.

"I thought we did as good a job on LeBron as we could," Stevens said. "But you have to pick your poison a little bit."

Game 2 of the best-of-seven series is Tuesday in Cleveland.

Olynyk had 10 points off the bench for Boston in a tight first quarter and the Celtics moved the ball well, getting nine assists on 12 baskets and shooting better than 57 percent. They led by eight after Smart's 3 in the first minutes of the second quarter.

But Cleveland -- behind 13 combined points from Love and Irving -- turned the tables with an extended 24-7 run keyed by consecutive 3s from Irving, J.R. Smith and Love. It gave the Cavs a nine-point lead.

Later, Irving crossed over another high draft pick, Turner, and knocked down his 3 from the high left side at the buzzer. The fourth-year point guard was 5-for-9 on 3s in the game.

"I thought we defended him really well on a couple of shots that he just hit," said Stevens. "The ones you (worry about) as a coach are not the ones they go Superman on you. The offensive rebounds kill you. The super-human shots do not."

Game Notes

Irving dropped 55 points against Portland on Jan. 28 and 57 points against San Antonio on March 12 in the two highest-scoring games in the NBA this season ... Tristan Thompson, also making his postseason debut, scored 12 points off the bench for Cleveland.