Waltham, Mass. ? Bill Russell, Bob Cousy and Red Auerbach are “walking through the door” for the Boston Celtics, who are back in the conference finals for the first time since the championship years of the 1980s.

The most successful franchise in NBA history, Boston has a supply of former stars like no other team. Now that the Celtics have restored some of the pride and swagger, players from years past have been showing up at FleetCenter.

Two years after coach Rick Pitino chastised fans with his infamous line that “Larry Bird is not walking through that door,” other stars are offering tips or just sitting in the stands and cheering.

“They give us a silent encouragement that we have to play up to par,” center Tony Battie said Friday. “To impress those guys, you have to put up a banner. They’re not impressed with any conference championship.”

Winners of a league-record 16 titles, the Celtics are well into the longest championship drought in team history. Before this year, Boston had not made the playoffs since 1995, had not advanced since ’92 and had not made it as far as the Eastern Conference finals since ’88.

For many, rock bottom came in 2000, when Pitino lashed out at fans for what he saw as unrealistic expectations after the Celtics had dropped 11 games under .500 and were eliminated from the playoff race for the fifth consecutive year.

As it turned out, the Celtics didn’t need Bird, Kevin McHale and Robert Parish to walk through the door as much as they needed Pitino to walk out of it. And since coach Jim O’Brien inherited the team in midseason last year, he has taken the team from its longest drought to its most impressive turnaround since Bird was a rookie.

With a 1-1 split in the first to games of the best-of-seven series against the Nets, the Celtics snatched home-court advantage from New Jersey; with a 10-game winning steak at home, they have a good chance to play in the NBA Finals for the first time since 1987.

They have not won it all since ’86.

The playoff run has been witnessed by a Hall of Fame who’s-who from Auerbach, Russell and Cousy to Bill Walton, K.C. Jones and Tommy Heinsohn. Russell, a bit of a grump in his playing days, is best known by these players for his hearty laugh and his locker room visits before and after games.

“I’m just glad to be a part of a history like that,” forward Eric Williams said, “and for him to know me by name.”

Russell and Antoine Walker also seem to have hit it off. Cousy, the former floor general, gives tips to point guard Kenny Anderson. M.L. Carr is in business with Walker and Williams. Heinsohn is courtside as a broadcaster, extolling the virtues of Walter McCarty.

For the Nets, though, the luminaries are just Boston fans destined for disappointment.

“They have waited for a long time,” guard Lucious Harris said.

Not since the franchise’s first years of existence had it gone as many as five years without winning a title, and its eight consecutive losing records until this season was more than the total in nearly half of a century.

Rather than add to the pressure to win, the old-timers try to make the players feel like they’re part of a family and a very happy and successful one at that.