Three words displayed Brett Brown's true passion.

The 76ers' coach said on Sunday that "I can't wait" to face the Boston Celtics in the Eastern Conference semifinal series. He repeated those three words to a reporter during Sunday's  media availability while leaving the session with the team's beat writers.

The Sixers will renew their rivalry with the NBA's most storied franchise at 8 p.m. Monday, and Brown loves it.

"I can't wait," he said. "You grew up watching Celtics-Sixers rivalries and saw incredible games when I was young.

"Even during my Boston University days, and to now be a part of that in the NBA playoffs in the semifinals and going back to Boston and the Boston Garden, absolutely, there is an element of nostalgia."

Philly, which has been waiting for an opponent since Tuesday, opens the conference semifinals at Boston's TD Garden. Game 2 will be Thursday night before the series heads to Philly for Game 3 on Saturday and Game 4 on May 7. This will be the Sixers' 20th time meeting the Celtics in the postseason dating back to the days in Syracuse, and the rivalry's history stretches from the great to the forgettable.

But this is the series many fans in Philly and Boston wanted to see. Facing the Milwaukee Bucks would have been nice for the Sixers. It just wouldn't compare meeting their Atlantic Division rivals with a berth on the conference finals on the line.

"I think just with the history that the two organizations have had give all of us enough ammunition to guess that that's going to be what lots of people wanted," Brown said, "and I think it's going to produce a fantastic series."

The Celtics won three of this season's four regular-season meetings. Boston won 102-92 on Oct. 20 in Philly; 108-97 on Nov. 30 in Boston, and 114-113 on Jan. 11 in London. The Sixers beat a Celtics squad minus all-star point guard Kyrie Irving, 89-80, on Jan. 18 in Boston.

For this series, Irving is sidelined due to season-ending surgery on his left knee. Jaylen Brown may miss time, too: He missed the entire second half of Saturday's Game 7 first-round victory against the Bucks with a hamstring injury and is listed as doubtful for Monday night.

Meanwhile, the Sixers are the hottest team in the NBA, winning 20 of their last 21 games. A lot of it has to do with the acquisitions of Marco Belinelli and Ersan Ilyasova after the February trade deadline.

The sharpshooters make the Sixers much different than the team the Celtics saw in October, November and January.

Surely their presence gives Philly an advantage?

"Yes and no," said Ilyasova. "But like I said, when you play playoff series, it's kind of different basketball, different mentality.

"We bring something as far as just come off the bench, bring extra energy."

Belinelli does, however, create a lot of scoring opportunities. So Ilyasova thinks he and Belinelli need to be aggressive on both ends of the floor.

They might have to, especially in the first two games in TD Garden. The Celtics are expected to receive a boost from their home crowd's energy.

As Ilyasova points out, it will be nothing like Game 3 and Game 4 in Miami during the Sixers' opening-round series against the Heat. Philly won both of those games, prevailing 4-1 in the series.

"The way it was in Miami, the gym was half empty," he said. "Those kind of things we don't expect.  But when you go to Boston, you will feel it, you know. You do in the regular season when you play there, the arena is full. They are really committed fans."

When he was with the Magic, JJ Redick faced the Celtics in the 2009 and 2010 postseasons. He said Boston's home arena gets as loud as the Wells Fargo Center.

"I still feel that those were as intense as any playoff games I've played in my career," Redick said. "The environment and the atmosphere was as loud as I've seen in my career. That's what we will all expect."

The teams' most recent postseason meeting came when the eighth-seeded Sixers took the Celtics to seven games during 2012 conference semifinals.

But one of the Sixers' hardest series losses to Boston came in the 1965 conference finals. Down 110-109, Philly tried to inbound that ball with 5 seconds remaining at the old Boston Garden. Celtics legend John Havlicek tipped Hal Greer's inbound pass to teammate Sam Jones, who ran out the clock. The Celtics went on to win a seventh consecutive NBA title.

Two years later, the Sixers recorded one of their most memorable moments against the Celtics in the 1967 conference final. Philly won the series 4-1, dethroning the eight-time defending NBA champions. The series ended with a 140-116 rout by the Sixers in Game 5. Philly went on to beat the San Francisco Warriors in six games in the NBA Finals.

But the Sixers suffered a series heartbreaker against the Celtics in the 1981 conference final. They had a commanding 3-1 series advantage only to lose the final three games by a combined five points.

Andrew Toney helped the Sixers avoid duplicating the heartbreak in the follow season's conference final. The Celtics, once again, forced a Game 7 after trailing 3-1. This time, the Sixers won the decisive game thanks to Toney's 34 points.

Boston went on to win the teams' next three playoff series meetings (1985, 2002, 2012) en route to holding a 12-7 series advantage.

"The '80s and the rivalry between Dr. J and [Larry] Bird that stands out," Redick said. "There's a deep history between the two teams and really two of the most storied franchises in NBA history. So it's obviously an honor to play in that rivalry."

The Sixers' Amir Johnson, Jerryd Bayless and Demetrius Jackson are all former Celtics.