LeBron James might be 48 minutes from free agency.

Technically, he’ll have to officially reject the player option on his contract, but that’s been a forgone conclusion since he signed his current contract three years ago.

But one loss, in Game 6 in front of what will surely be a raucous crowd at the Boston Garden, and the Cleveland Cavaliers will no longer have a leash on the league MVP.

That statement alone sparks an adrenaline rush in Cavs fans, shivers creeping down their backs.

Unfortunately for them, it hasn’t had the same effect on their beloved team and superstar.

Urgency. It’s a word that applies to all facets of life, whether it’s taking an ill relative to the emergency room, cramming the night before an exam or playing with fire in a game that could swing a postseason series in one team’s favor and also send the best player in the NBA bolting the city for another market.

The Cavs played with as much passion and tenacity in Game 5 as the elderly do on bingo night.

That lack of fire starts with one person who needs to set the Garden ablaze in Game 6: LeBron.

It’s LeBron’s Cleveland clock ticking toward zero. No one is more aware of the chance that he won’t be sporting wine and gold two months from now.

But forecasting July’s events should wait until after the postseason.

LeBron might never have a supporting cast as talented as the one that serves him now.

Sure, Mike Brown makes unjustifiable substitutions, can’t decide on a rotation and has been severely outcoached by Doc Rivers.

But The King’s drama-queen persona has placed LeBron on a pedestal, high above his coach on the Cavs’ totem pole. It’s LeBron’s team. He, not the coach, is the leader.

If the Cavs can’t stop the bleeding tonight, Brown will probably lose his job. But make no mistake about it — owner Dan Gilbert, GM Danny Ferry and just about every Cleveland fan will throw themselves at King James between then and July 1.

The Celtics have earned recognition as the gritty, veteran group that “knows how to win.”

But the Cavs play a number of seasoned veterans as well. Shaquille O’Neal has more rings (four) than the Celtics’ vaunted “Big Three” of Kevin Garnett, Ray Allen and Paul Pierce has combined (three). LeBron, Brown and several other Cavs reached the NBA Finals a mere three years ago.

However, it’s the mindsets of the two teams that has one side exceeding expectations and the other on the brink of a city-wide Armageddon, the largest, most catastrophic meltdown since Chernobyl.

The Celtics have summoned the swagger that pushed them to a championship 23 months ago. The Cavs strolled the floor at The Q Tuesday night boasting an undeserved sense of entitlement, as if even a subpar effort would do the job.

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Does LeBron care more about marketing his services to the most attractive suitor in two months than he does about winning postseason games that aid in defining his basketball legacy? His passive, uninspired play in Game 5 favors the former.

LeBron’s actions and mannerisms rub off on his teammates more than any player in the league. His teammates take part in his intricate handshake routines, they join him in dancing away the fourth quarters of blowouts and they model their on-court resolve after their fearless leader. The ineffectiveness and timidness displayed by Mo Williams, Delonte West, Antawn Jamison and others are as much a reflection on LeBron as they are on the individuals themselves.

If LeBron was a movie director, then Game 5 was his Blair Witch Project (although for Clevelanders, it was actually scary).

After a scoreless first half, LeBron continued his submissive approach after intermission. His first basket — a soft dunk off of a cherry-picked fast break midway through the third quarter — epitomized his lackluster effort.

And LeBron’s post-game demeanor didn’t exactly offer any hope to Cavs fans searching for a killer instinct somewhere within his 6-foot-8-inch, 260-pound frame.

“I spoil a lot of people with my play,” he said. “When you have three bad games in seven years, it’s easy to point them out.”

In other words, “Cleveland, appreciate what I’ve brought you, not what I haven’t brought you.”

As the adage goes, “You don’t know what you have until it’s gone.” But Clevelanders don’t have to wait until LeBron departs to know what they don’t have — a championship team that actually lives up to haughty expectations.

“I put a lot of pressure on myself to be out there and be the best player on the court, and when I’m not I feel bad for myself because I’m not going out there and doing the things I can do,” he said. “But I don’t hang my head low or make any excuses about anything that may be going on, because that’s not the type of player or person I am.”

Not exactly the fired-up, PO’ed attitude we expect elite talents to convey after monumental defeats.

This loss didn’t officially end the series, but LeBron’s actions and words suggest that the end of an era might be just around the corner.

Entering Game 5, the general consensus indicated that LeBron would likely stay in Cleveland, where he starred on a perennial championship-caliber team with a spend-happy owner.

After one, landscape-altering performance, that conjecture has taken a 180.

That dramatic switch is all on LeBron. And maybe that’s the way he prefers it.

But if Michael Jordan had trailed at halftime of a must-win game on his home court, he would have taken it upon himself to motivate his troops and embrace his role as pilot.

Instead, LeBron is driving the Cavs’ plane into the ground.

There’s still a small amount of time to re-route it onto its expected path. The city of Cleveland anticipates a crash landing. But if the plane goes down, LeBron, the pilot, could be the lone survivor.