James Harden says the Brooklyn Nets are a "very, very special group" after securing a 4-1 NBA first round playoffs series win over the Boston Celtics with a 123-109 win on Tuesday.

The Nets progress to the Eastern Conference semi-finals where they will face Giannis Antetokounmpo and the Milwaukee Bucks who swept the Miami Heat 4-0.

Harden had a 34-point triple-double as the Nets' 'big three' got more game-time together, with Kevin Durant and Kyrie Irving having 24 and 25 points respectively.

"We're a special group especially when we lock in defensively," Harden told ESPN post-game.

"When we can get three-four stops in a row, we're a very, very special group. Offensively we can get it going, we've got that much firepower."

Harden was also delighted to get more minutes alongside Durant and Irving, having missed 18 games late in the season with a hamstring injury.

"We've had so much adversity, injuries, COVID protocol, whatever it may be, we've dealt with a lot of adversity throughout the regular season so it felt good to get some meaningful games in," Harden said about the Boston series.

"Obviously in playoffs you don’t want to lose. It helped us out in the sense that it's time to lock in now.

"Tonight was a really good job. They're a really good ball team. They were down a few players but they kept fighting."