Practice has been over for an hour, but there was Rajon Rondo working on his jump shot. From angles and distances all over the court, Rondo took shot after shot, being fed a steady supply of passes from assistant coach Armond Hill.

Toward the end of the session, Hill had a variation on the drills. He would throw a pass to a spot on the floor where Rondo would track it down, square himself up and shoot. “Make ten,” Hill said. As he approached the number, Rondo said back, “Ten more.”

On and on he shot, breaking up the jumpers with trips to the free throw line.

He knows, as does everyone else in the league, that those jumpers and free throws hold the key to the Celtics fortunes in the postseason. Rondo got a taste of the various defenses that will be employed against him in the postseason Thursday in a loss to the Lakers.

It’s a familiar tactic by now. Kobe Bryant sagged 10 feet off him and tried to disrupt passing angles and driving lanes with his long and active reach. When Rondo did drive, there were two 7-footers waiting for him in Andrew Bynum and Pau Gasol.

The Lakers are better equipped to play this defense than most because Bryant is such a smart, active defender and because the 7-footers have learned to adjust to Rondo. They now wait that extra split-second to make Rondo commit before committing to him. 

Very few teams can employ that kind of talent and length against Rondo, but they all will try.

On Sunday against Miami, the Heat will present Rondo with different looks. Maybe it will be Dwyane Wade. Perhaps it will be LeBron James. The Heat don’t figure to play their so-called point guards – Carlos Arroyo and Mario Chalmers – much against Rondo since he has already eviscerated them twice this season.

“If we play right, at the right speed, I said it to you guys and I know you get sick of it, but of all the teams in the league I don’t know if anybody’s more tied to their defense,” Doc Rivers said. “If we want to avoid teams helping and zoning us up, then we’ve got to get stops where we can get [Rondo] the ball and play in transition.”

That’s one way to counter those defenses, since there isn’t a scheme in the world that can stop Rondo with a full head of steam. The other, obviously, is the jump shots. 

Rondo has expanded his range this season, taking more long jumpers than ever before. He’s also making them at a better clip than his past history suggests, but accuracy on long jump shots is one of the most inconsistent NBA traits in a very consistent game.

Even if he somehow turns into Steve Nash overnight, teams will continue to try to make Rondo beat them from the outside. With all the criticism he took in the wake of the Lakers loss, it’s worth remembering that even with this obvious weakness, Rondo is one of the elite point guards in the game.

He has found ways to compensate for his lack of a reliable jumper and it’s unwise to wager against his resourcefulness and creativity. If the injury-ravaged Celtics are going to beat the Heat on Sunday, Rondo will have to be at his best.

He is the one player in this matchup that doesn’t have an effective counter. Chalmers and Arroyo have as much chance of staying with him as did Derek Fisher and Steve Blake, and the Heat don’t have a combination like Bynum and Gasol inside.

They do, however, have Mike Miller and the veteran swingman has been an invaluable addition since returning from a thumb injury. Since Miller has returned and begun playing regular minutes, the Heat have won eight straight and none of their last 10 games.

“He’s another versatile player who can spread the floor,” Paul Pierce said. “Very high basketball IQ. He compliments LeBron and Wade very [well] for the simple fact that he can guard two or three positions.”

Heat coach Erik Spoelstra can employ a lineup that features Miller, Wade and James without a nominal point guard, which would leave Rondo guarding a much bigger opponent.

“We don’t mind that,” Rivers said. “As long as we get stops. If we get stops when they have a bigger lineup that means Rondo’s going to be in transition with one of those three guys trying to stay in front of him. That’s all right by us.”

The Celtics don’t want to get into a grind-it-out game with the Heat. They want to run and if they can, that’s Rondo’s kind of game.

Here are four other things to watch for Sunday:

WHO GUARDS LeBRON?

The answer is Paul Pierce. The better question is: Who guards LeBron when Pierce is out of the game? There is no good answer to that question.

“Whenever you defend LeBron anyway it’s not going to be with just one guy,” Pierce said. “It’s not going to be just Paul Pierce defending him. It’s got to come from all five guys and we all know that. There’s no one guy that can stay in front of him and guard him.”

Pierce absolutely, positively can not get into foul trouble in this game. Without Marquis Daniels to back him up, the Celtics are woefully short at the position. Von Wafer isn’t really that guy and Glen Davis would be playing out of position, but he may get the chance.

“When you’re shorthanded the approach is not to get into foul trouble,” Pierce acknowledged. “If I get in foul trouble it’s tough on us.”

KEVIN GARNETT ON THE POST

If there was one thing that drove Rivers crazy in the loss to Lakers, it was the Celtics over-reliance on jump shots. The Lakers outscored them 50-32 in the paint, and when the jumpers stopped falling, the Celtics couldn’t score.

Without Shaq, the Celtics best post player is Kevin Garnett, who is shooting almost 76 percent at the rim this season. In their earlier meetings against Miami, Garnett had his way with Chris Bosh defensively, but didn’t need to do much damage inside.

That will have to change Sunday if the Celtics are going to go back to being an inside-out team.

DON’T TURN IT OVER

Fortunately for the Celtics, if there’s one thing the Heat don’t do very much, it’s force turnovers. The Heat rank 26th in turnover rate, which is a good thing for the turnover-prone Celtics.

But when the Heat do get turnovers, and Wade and James are in the open floor, there’s nothing to do but watch the show.

“It reminds me of Jordan and Pippen out on the break,” Pierce said. “Once they got on the break it was almost like they were unstoppable. Same case here. You cause turnovers, you might as well put in two points for them.”

Again, with their depleted roster, the Celtics have to play an almost perfect game to beat Miami. That will require taking care of the ball. 

WHAT DOES IT MEAN?

As with the Lakers, this one probably means more to Miami than it does to the Celtics in the big picture. The Celtics already own two wins over Miami and let’s be honest, they’re one more injury away from catastrophe.

That doesn’t change the fact that the Heat are now in first place by half a game in the Eastern Conference standings and that the Celtics have lost two straight for the first time all season and three of their last four.

“We have something to prove to ourselves,” Pierce said. “We want to play better basketball, more consistent basketball than we have of late. We’ve got to be able to put together two halves. This is a big game for us.”

The Celtics have almost no margin for error. They can’t get into foul trouble and their starters are probably going to have to play extended minutes because the bench is basically nonexistent after Glen Davis.

This stretch was supposed to be a referendum on the Celtics, but after losses to the Mavs and Lakers this is more about survival than anything else. But as long as they put their four All-Stars on the court they have a chance against anyone.  

The Celtics have proven to be a dangerous team over the years when backed into a corner and their room to breathe is getting tighter and tighter.