Of all the playoff matchups and all the possibilities, the Celtics and Heat are the one that seemed predestined from the moment LeBron James signed with Miami. More than half of the Eastern Conference All-Star team will be on the floor and the storylines began taking shape minutes after the Heat got past Philadelphia on Wednesday.

Consider just a few of them from the Miami side of things:

Can James finally beat the Celtics in a playoff series? Since reaching the NBA finals in 2007, James’ teams have gone 5-3 in the playoffs with two of those losses coming against the Celtics. His teams have won two series against No. 8 seeds and one each against a seven, five and four.

Will the Heat trust each other in crucial moments, or will the veteran Celtics teach them a few lessons about the subject?

Can Chris Bosh compete with Kevin Garnett on a nightly basis and match his manic intensity?

The Celtics come into this series with their own set of questions: Do their veterans have the juice to keep up with Miami’s younger legs? Can the second unit find its rhythm? Will Jermaine O’Neal stay healthy and productive?

All that and we haven’t even mentioned Shaquille O’Neal who won a championship with Dwyane Wade in Miami and played with James in Cleveland. If Shaq can get on the floor and contribute, he could alter the whole complexion of the series. But that’s at best a 50-50 proposition and probably not even that high. 

This is as good as its gets in the conference semifinals, and maybe in the whole league. Each of the four games they played this season have been contentious and with the exception of the final meeting that ended in a Heat blowout victory, they have all been close.

As we begin to unravel the matchup, here are three key players for the Celtics, numbers to track, possible X-factors and a prediction: 

RAJON RONDO

Rondo recaptured his game – and a good bit of his reputation – with his masterful play against the Knicks in the first round. He averaged 19 points, 12 rebound and 7.3 rebounds, but more importantly he played with the kind of speed that is demanded of him to be great.

“It’s night and day when you see it,” Ray Allen said before the team’s practice on Wednesday. “When he’s out there and he’s going and he’s got the energy, whether you make a shot or not he’s still having an impact on both ends of the floor. He’s on us about running the floor. I’m thinking I’m running, but let me run a little bit harder.”

This isn’t all on Rondo. Even casual observers of the Celtics understand that they are individually less than the total sum of their parts. Their offense doesn’t revolve around sets and plays as much as it does around their respective talents.

Allen works off screens, Kevin Garnett sets picks, spaces the floor and goes to the post when needed, Paul Pierce does a little bit of everything and Rondo runs. If one thing is out of sync then the whole operation sputters into an unsightly mess of forced jump shots and poor spacing. 

“His speed does everything for everybody,” Allen said. “Everybody has to do what they do. Everybody has to do their jobs. There’s something that each one of us does that helps the other guy out.”

Or as Doc Rivers put it, “This really is a team that is pretty much tied together and each guy has to carry his own load.”

And yet, while all that is true no one has had a bigger impact on the Celtics’ offense over the last two months – both positively and negatively – as Rondo. He is also the single biggest matchup problem in this series for both sides. Mario Chalmers emerged against Philadelphia as the Heat’s best small guard option over Mike Bibby, but can the Heat trust each other to stay with a revved up Rondo?

You can expect the Heat to use Dwyane Wade on him at times as well as LeBron James. That, in turn, will open up other matchups and the chess match will begin. It all revolves around Rondo. 

He’s seen all the looks before, but he won’t see anything like the passive, non-challenging defense the Knicks employed against him. Miami is one of the best defensive teams in the league and this will be a huge test for him.

JEFF GREEN

Among the many reasons Danny Ainge executed the trade that sent Kendrick Perkins to Oklahoma City was the chance to get more versatile with the addition of Jeff Green. Ainge didn’t necessarily make the deal with this series in mind, but it did factor into his thinking.

Green had an up and down series against the Knicks, but he did show flashes of inspired play. Now he must perform consistently. “I thought Jeff played great the last couple of games,” Rivers said. “He’s doing a lot of things that we need him to do.”

Among the things they want him to do is post-up. Rivers called his number on several low block opportunities against the Knicks and he hinted there may be more in the future.

“The one thing the [second unit does] well is post,” Rivers said. “That second group is a great post group. Jeff Green, Delonte [West] and [Glen Davis], so we have to try to run a package more suited to them.”

Rivers added that Green may wind up playing more with the four starters. “The other fifth guy is Jeff Green,” he said. “That may be our biggest plus of all the groups but we just haven’t used it a lot.”

They’ll get the chance against the Heat who have used lineups with James, Wade and James Jones on the floor with a small guard and a big man. Green will be tested both offensively and defensively in this series, and you can bet that how he plays will go a long way toward shaping opinion on the trade.

PAUL PIERCE

From Carmelo Anthony to LeBron James, that’s Paul Pierce’s lot in life. Not that he doesn’t love the challenge, but this will be his biggest of the postseason. As great a scorer as Anthony is, he doesn’t possess the all-around game that James does and he is nowhere near his class defensively.

Pierce played well against the Knicks – Anthony’s 42-point Game 2 outburst notwithstanding. He averaged 22 points and four rebounds while shooting 50 percent from the floor and from 3-point range. Anthony went for 26 and 10 in the series, but Pierce made him work for it holding him below 40 percent from the field and 33 percent from 3-point range. The Celtics will take that kind of trade-off with James all series long, if Pierce can do it.

In last season’s playoff matchup with the Cavaliers, James outplayed Pierce in five of the six games and often decisively. James outscored him 161-81 and beat him on the boards, 56-29. Pierce fared slightly better during the regular season but James still averaged 29 points and almost seven rebounds per game, while Pierce was held to 17 and five.

There’s no Tony Allen waiting in the wings this year and relief will have to come from Green. Rivers said he was happy with the way Green defended Anthony in the first round. He and Pierce will have to be even better in this series. 

THREE KEY STATS

Turnovers: This has long been the Celtics biggest problem offensively and they didn’t do a good job managing it in the first round, committing almost 17 per game against the Knicks. The Heat don’t actively force a lot of turnovers and if the Celtics are committing them, that means they are doing a poor job taking care of the ball. James and Wade are two of the NBA’s best finishers on the break and the Celtics can’t give away easy points.

Defensive rebounds: In their late-season loss to Miami, the Celtics allowed 15 offensive rebounds including nine to Zydrunas Ilgauskus and Joel Anthony. Like turnovers that lead to transition baskets, the Celtics can’t afford to give up second-chance points.

3-point shooting: Miami ranked seventh in the league in 3-point accuracy at 37 percent. The Heat struggled against Philadelphia until Chalmers went off in Game 5, but this is a battle the Celtics have to win because they don’t get to the free throw line nearly as well as Miami.

X-FACTORS FOR THE CELTICS

Jermaine O’Neal: If he can provide the kind of defense, toughness and occasional offense that he brought against the Knicks, then the Celtics will be fine inside, but he has to rebound better.

Ray Allen: He’s more than an X-factor, but Allen has played Wade tough over the years and if he can stay hot from the outside that would help open up the floor for his teammates.

Delonte West: He went under the radar during the Knicks series, but he’ll have to be better in this series. The Celtics will need him to help defend Wade and also spell Rondo.

X-FACTORS FOR THE HEAT

Joel Anthony: Miami played much better when he was on the floor against Philadelphia and he killed the Celtics in their late-season meeting. Anthony is limited offensively but he’ll make his mark defensively and on the glass.

James Jones: The one killer 3-point shooter on the wing now that Mike Miller has slipped out of the rotation. James is deadly from long range and he’s a player the Celtics will have to be mindful of when he’s on the court.

Bibby/Chalmers: The pressure will be on them to help contain Rondo and also knock down jump shots. Rondo loves to help off point guards and gamble for steals who aren’t threats to penetrate. He’ll have to be aware of where they are on the floor and not give up easy looks.

THE SCHEDULE

This is a series that promises to have chaotic mood swings from one game to the next. The Celtics aren’t afraid of going to Miami and winning on the road, but in order to pull this off they’ll probably have to win two games away from the Garden. They get a break with a three-day rest between Games 2 and 3 and if it goes seven games, they’ll have two days to recuperate.

PREDICTION

When the regular season ended, Miami looked like the team to beat while the Celtics looked old and vulnerable. Then the Heat lost Game 4 in Philly and were taken to the wire in Game 5 raising old doubts about their focus and ability to close out games. Meanwhile the Celtics took care of business against New York, finishing a sweep of that series on the road. The perception seems to have shifted, but absolutely none of that matters when the two teams tip on Sunday afternoon.  

The Celtics will have to be at their very best to beat the Heat and outside of Game 3 and two and a half quarters of Game 4 they have not been that yet. This is a classic NBA matchup of new versus old. The Heat always knew they would have to go through Boston, the way the 2008 Celtics knew they had to get through Detroit.

It’s all shaping up for a seven-game classic and while it’s NBA hearsay to go against the home team in that situation, the bet here is that the Celtics get it done on Miami’s floor. The pick: Celtics in seven.