But there is also the chance that Boston's experience and wisdom aren't as intimidating as they used to be, and that the 76ers won't be in awe so much as they will be inspired to exploit the Celtics' injuries and age.
"You've got to go get it still -- you've got to go play,'' said Boston coach Doc Rivers, dismissing hope that a seventh-game aura will carry his team through. He was more concerned with the mundane realities. "I do like that we have an extra day," he said of the two full days of rest leading up to Game 7 here Saturday night. "I think that helps us a little bit."
[Zach Lowe: Game 7 looks like toss-up]
Every advantage matters after Philadelphia's 82-75 victory in Game 6 on Wednesday, when the 76ers defended their home court while showing the poise they've acquired over the last month. After barely hanging on to make the playoffs as the No. 8 seed, they took advantage of Derrick Rose's season-ending knee injury (along with a subsequent ankle injury suffered by center Joakim Noah) to finish off the top-seeded Bulls in six games. They've provided stubborn resistance throughout a conference semifinal that the Celtics believe they could have swept.
Boston's worst fear is that the Sixers will play Game 7 without anxiety -- as if they have nothing to lose and everything to gain. If the moment liberates them, then good luck to the Celtics' hopes of surviving Philadelphia's advantages in athleticism, energy and depth.
"That's the beauty of youth," Philadelphia coach Doug Collins said. "They look at things a little bit more naively, and maybe not as much analytically as I do. I just want our team to play with no fear. I want us to be tough at the defensive end and I want us to play free on offense."
The recent growth spurt of his young team overwhelmed the Celtics in Game 6, when the 76ers bottled up Rondo and controlled the game defensively. They played like an older team on young legs.
"Late in the game when it was tight,'' Collins said after Game 6, "I looked down and a couple of our guys were smiling. They were enjoying the moment. That's the beauty of competition. We're playing the Boston Celtics, let's see what we can do. I love that with our young guys.''
The 76ers lack a go-to scorer, but over the course of this series they've turned that weakness into a strength by attacking from a variety of positions. In Game 6 they took advantage of the absence of defensive stopper Avery Bradley -- whose shoulder injuries will sideline him for the rest of the season -- to pierce the perimeter and score down the stretch. No one but Jrue Holiday (20) generated more than 13 points for Philadelphia, but a half-dozen Sixers scored nine or more.
[Gallery: NBA's memorable Game 7s]
The Celtics need to control the pace so that Rondo can dictate the game in the open floor and create easy shots for Kevin Garnett, Paul Pierce and Ray Allen. It will be a good sign for Boston if Garnett is running hard in transition to establish early post position near the basket, because Rondo will feed him every time and the Celtics will be able to create the inside-out game they desire. Rivers also drew faith from the 76ers' defensive change of leaving a struggling Allen and making him prove that he can overcome his ankle injury to punish them from the three-point line. Allen missed four of his five threes Wednesday, though he did produce a big one in the final two minutes after reaching out to catch an inaccurate pass.
"They didn't face-guard Ray -- they allowed him to get loose. He just didn't make shots,'' Rivers said. "It will be good for Ray now that he knows he's going to get shots."
The Celtics are 17-4 in seventh games at home, though that historical perspective will mean little to these 76ers. The impact was minimal when Collins prepared his players for Game 6 by showing video of Game 7 of the 1982 Eastern Conference finals, in which the 76ers (for whom Collins played from 1973-81) won famously in Boston after surrendering a 3-1 series lead.
[Gallery: Classic photos of 76ers-Celtics rivalry]
"These guys are so young,'' said 76ers forward Elton Brand, 33. "They didn't know what was going on."
"Half of these young guys don't know I played," Rivers joked, "and they definitely don't know Doug played.''
The winner will move on to the conference final in Miami on Monday. If the loser is the 76ers, then they can be inspired by pushing themselves along this far. And if it's the Celtics, then the Big Three era may have come to an abrupt and unexpected end.