Mike Celizic

The Heat, both literally and figuratively, are on Shaquille O’Neal’s shoulders now, and if he can carry Miami into the playoffs and on to another NBA Finals, it would be the greatest accomplishment of his singular career.

The reason is that he’s going to have to do it alone. When Dwyane Wade went down with a separated shoulder, Shaq, who was just coming back from knee surgery himself, lost his support system.

It’s an enormous request. The Heat are an old team, and Wade’s replacements are going to be Eddie Jones, who’s 35, and James Posey, who’s 30. Shaq himself turns 35 next month, and point guard Jason Williams is 31. Alonzo Mourning, Shaq’s backup, is 37.

What made the team a champion was its veteran savvy, Shaq’s enormous presence in the middle and Wade’s extraordinary ability to score and create openings for his teammates. When Shaq was out for the first half of the season, the team struggled. Since he’s returned, they’ve started to play better and when Wade went down held the eighth and final playoff spot in the East, two games clear of the Nets.

Fortunately for Shaq, the Heat are in the East, which has fallen on hard times. The Heat probably won’t have to play more than a couple of games over .500 to make it into the playoffs, which begin in seven weeks. By then, a well-rested Wade should be back (barring season-ending surgery), and with Shaq and Wade both in the lineup, playoff seeding doesn’t mean a lot.

But the pressure on Shaq is two-fold. First, he has to get the Heat to the postseason. Second, he has to do it without injuring himself.

That’s hardly as easy as it sounds. If there’s been one consistent feature of his career, it’s his ability to get injured. Shaq has played more than 67 games in a season just once in the past five years. That was in 2004-2005 when he made it to 73 games. In the 11 years since 1995-96, his fourth season, he’s played more than 70 games just three times. And when he has played, he’s frequently been nursing various injuries.

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He may be the biggest and strongest man in the game, but he’s not the most durable. And now, the Heat can’t afford for him to pop a groin, bruise a thigh, pull a hammy or suffer any of the other maladies that have sidelined him so often in the past. At the same time, he’s going to have to play hard and put in a lot of minutes. It could be a recipe for disaster.

But it’s the only recipe Pat Riley, the coach who just returned to the bench after his own injury time out, has in front of him. And Riley of all coaches knows what he’s up against.

It would be nice if he could look elsewhere for help, but Wade was putting in more than 28 points a game, and nobody has that kind of scoring just sitting around on the bench, waiting for its moment. Only Shaq can replace it.

But the history of Shaq is the history of all the big men: if he has great help, he’s a champion. If he doesn’t, he isn’t.

In Los Angeles, he was part of a dysfunctional but very successful inside-outside championship tandem with Kobe Bryant. In Miami, he returned to the top last year thanks to another great outside man — Dwyane Wade.