The opponent they would face in the first round of the playoffs, however, remained a mystery, though the team had potential opponents in mind.

"We've been looking at Philly obviously with the idea that they're a likely opponent," coach Brad Stevens said.

"And they're a heck of a team."

That foresight has played out as the Celtics get set to take on the Philadelphia 76ers in Game 1 of their best-of-seven series.

The Celtics were 1-3 against the 76ers during the regular season, though Philadelphia will take on a different complexion in the playoffs with All-Star guard, Australia's Ben Simmons, sidelined following knee surgery.

"In the games that Simmons hasn't played, they're the No. 1 offence in the league," said Stevens.

"The spacing, the shooting around (Joel) Embiid posting, the ability to play big with both Embiid and Al (Horford).

"A bunch of shooters around them makes them very tough."

The 76ers went 4-4 during the seeding portion of the NBA season restart, ending on a 2-3 stretch in the games without Simmons.

The 76ers lost in the conference semi-finals last season, falling by two points in Game 7 to the eventual champion Toronto Raptors.

"Now is our moment," Sixers coach Brett Brown said.

"Now is our time to be recognised. I'm happy with the way we're playing the game -- I think there's a great unity within the group."

Though there is no home-court advantage in the NBA bubble, the playoff format will largely stay the same, with teams playing every other day.

Each series will be best-of-seven through the NBA Finals, which are set to conclude no later than October 13.

The last time the Celtics and 76ers met in the playoffs was 2018, when Boston won 4-1 in the conference semi-finals.

Australian Associated Press