As expected, Boston and Philadelphia will meet in the postseason this year. But the sport in which the two cities will do battle is a surprise.

While baseball’s Red Sox and Phillies (each touted as World Series contenders prior to the season) continue to languish at or near the bottom of their respective divisions and the NHL’s Bruins and Flyers (who dueled in a classic 2010 series in which the Flyers beat the Bruins by storming back from a three games to none deficit) are each home for the summer, the Boston Celtics and Philadelphia 76ers will renew one of basketball’s great playoff rivalries in the Eastern Conference semifinals.

The Celtics edged the 76ers, 92-91, in Game One of the best-of-seven series Saturday, May 12. Game Two is scheduled for tonight, May 14, in Boston before shifting to Philadelphia for Games Three and Four Wednesday, May 16 and Friday, May 18.

Such a matchup appeared unlikely at best when the 76ers sneaked into the playoffs as the eighth and final seed in the East, but their path opened up when the top-seeded Chicago Bulls lost star point guard Derrick Rose to a season-ending knee injury in the waning moments of the Bulls’ Game One win. The 76ers ended up ousting the Bulls in six games.

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The fourth-seeded Celtics, meanwhile, completed their six-game win over the fifth-seeded Atlanta Hawks the same night the 76ers dispatched of the Bulls to set up a series thick with 1980s nostalgia.

The Celtics and 76ers split the four Eastern Conference finals they played in a six-year span from 1980 through 1985. The rivalry peaked during consecutive seven-game series in 1981, when the Celtics came back from a three games to one deficit and knocked out the 76ers by winning the final three games by a combined five points, and 1982, when the 76ers once again raced out to a 3-1 lead but needed to beat the Celtics in Game Seven in Boston to advance to the NBA Finals.

As heated as things became between the two teams — in 1984, Celtics star Larry Bird and 76ers star Julius Erving would exchange blows during a regular season game — the Celtics and 76ers, as well as their fans, were bonded by one common enemy: The Los Angeles Lakers. In fact, the infamous Boston chant of “Beat L.A.!” started as Game Seven wound down in 1982 by Celtics fans expressing their support for the 76ers and their upcoming NBA Finals battle against the Lakers (who, alas, beat the 76ers in six games).

Now, perhaps it is time for another generation of players and fans to get a taste of how intense Celtics-76ers games can be in the playoffs. This marks just the second time since 1985 that the teams have met in the postseason — the Celtics edged the 76ers, three games to two, in a first-round series in 2002.

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