MIAMI — At this point it is no longer about adjustments, strategies or X’s and O’s. The Celtics know what they have to do against Miami — limit turnovers, hit the defensive boards, protect the paint. They just haven’t always successfully executed the game plan.

All of that will be important to determining the outcome of Game 5 on Wednesday night, but the real key for the Celtics lies in a deeper, more primal portion of their brains. Simply, how much more do they have left, and how much more can they give?

This isn’t about heart or courage or any of those other shopworn clichés — they proved their resiliency already and have proven it time and again during this run. But it is about human nature and it’s also about all the advantages the Heat have shown throughout this series. If the C's can avoid a bad start, something that plagued them in the first two games of the series in Miami, and put themselves in a position to grind it out, then they will give themselves a fighting chance to prolong the series. If not, the inevitable may set in.

“Just try to win one game,” Rajon Rondo said in a somber Celtics locker room after Game 4. “Simple as that.” 

For the Celtics it really is that simple. Try to win one here and take it back to Boston. It’s a daunting task. Only eight teams have rallied from 3-1 deficits to win playoff series, and only two — the 1995 Rockets and the 1968 Celtics — have done it without homecourt advantage.

Despite the C's long odds, the pressure realistically is on the Heat to finish things now. “This is not a team you want to let your guard down against,” Dwyane Wade told reporters on Tuesday. They don’t want any part of coming back to Boston or facing a do-or-die Game 7, even if it is on their home floor.

The Celtics don’t have to win three games on Wednesday, they only need to take one, but it may be the hardest one to get. Here are three more things to keep an eye on in Game 5.

WHAT CAN RONDO GIVE?

If there’s one thing Rondo earned with his gritty Game 4 performance, it’s a lifetime pass in the benefit of the doubt club as it relates to his health. He was clearly hurting (and limited) throughout his 38-minute performance, although he would just as soon admit that as subject himself to a 15-minute interview. Time and again Rondo bounced off screens, drove into contact and even hit the floor on his dislocated elbow. Time and again he bounced back up and kept going.

“I don’t even know how he’s still playing,” Paul Pierce said. “But I expect him to grind it out. It’s all on the line.”

Rondo steadfastly said he is playing in Game 5, but again, the question is how much can he give and at what point does having a primary ballhandler with one good arm help or, more accurately, hurt his team?

Kevin Garnett noted that he couldn’t deliver passes to Rondo with the usual zip and there were many times when he simply handed off to Pierce and either hovered near the basket or went to the corner where his man could easily leave him and double whoever did have the ball. 

“It was a hell of a dilemma all game, whether he was helping your team, hurting your team,” Doc Rivers said. “You kept going back and forth with it. The one thing I was surprised was how well he played defensively. I was far more concerned with that and I thought he did pretty well.”

As with Game 4, the Celtics won’t know how helpful Rondo can be until the game starts, and you can bet Rivers will keep a close watch on how he performs.

CAN KEVIN GARNETT FIND REDEMPTION?

It’s unfortunate for Garnett that just 48 hours after he delivered one of his finest performances as Celtic, he was held up as the primary reason they lost Game 4. Whether it was his 1-for-10 shooting or the miscommunication mistakes that plagued him on both ends of the floor, Game 4 was hardly his finest hour.

The game plan won’t change. The Celtics need Garnett to be a monster on the block and quarterback the defense on the other end. For most of the night he was spectacular on the defensive end, but an ill-fated switch on LeBron James allowed Chris Bosh to sneak in for a weakside tip-in that sealed the Celtics' fate, and the failure to execute a last-second play has been well-documented.

Outside of Game 3 when he dominated Bosh, Garnett has not won his matchup. Bosh played him even in the first two games and outplayed him in the second half of Game 4. If the Celtics are to have any chance, Garnett has to be great.

WILL THERE BE AN X-FACTOR FOR THE CELTICS?

Glen Davis is lost, Shaquille O’Neal is hobbled and Nenad Krstic is on the bench. If any of those three can give the Celtics anything it would go a long way in helping their quest. Davis, in particular, has to find his game, and himself, quickly. The Celtics are running out of patience with him but he’ll keep getting chances if only because there is very little behind him.

Maybe it will be Delonte West, who was terrific in Game 4. Or maybe it will be Jeff Green who has shown some positive signs. Either way, one of those players has to deliver a great game for the Celtics in Game 5 because the starters need some help.

The Heat’s big three took 63 of their 79 shots and scored 83 of their 98 points in Game 4 in what was easily their finest hour collectively to date. It’s taken everything the Celtics’ big four have between them to simply try to match that production. Unless one of the C's role players comes through, matching them won’t be enough.