As the Celtics  returned to practice on Wednesday they still don’t know who their next playoff opponent will be, but that gives them a chance to focus on what has been their toughest adversary at times this season: themselves.
“I’ve told you all year our opponent has been us, so we get a chance to work on our stuff,” Doc Rivers  said. “[This week is] very similar to training camp. When you start camp you really don’t have an opponent.”
That said, they clearly have an eye on Miami, who has a chance to close out its first round playoff series with Philadelphia on Wednesday night. As long as there’s not a Game 7 in that series, the Celtics will be in Miami for Game 1 on Sunday.
In the interim, their focus will be on what they do, especially their reserves. Glen Davis , for one, isn’t lacking any confidence.
“I feel like our bench is way stronger than theirs,” Davis said. “We’re way deeper than them. We just have to make sure we use our depth.”
The Heat have primarily used three reserves in their first round series with Philadelphia — Joel Anthony , Mario Chalmers  and James Jones  — but they may get a boost if Udonis Haslem  is able to return from foot surgery that has kept him out since late November. An ineffective Mike Miller  has fallen out of the rotation.
The Celtics may be deeper on paper, but their second unit didn’t exactly distinguish itself in their series with the Knicks except for a strong showing in the first half of Game 4. Rivers feels like he has gained some insight from that series, however.
“We knew what the starters could do,” Rivers said. “We weren’t sure what the fifth guy with the starters could do and you had no idea going into a playoff series what your bench, not only what they were going to give you, but what worked for them. As the playoffs went on we kind of figured out more and more what they’re comfortable with, what they can’t run more than what they can run.”
Despite their struggles, Rivers was encouraged by some of what he saw in New York, particularly on the block. “The one thing they do well is post,” Rivers said. “That second group is a great post group. Jeff Green , Delonte [West ] and Baby, so we have to try to run a package more suited to them.”
The Celtics don’t incorporate a lot of post-ups in their offense, mainly because they haven’t had a reliable presence on the block since Shaquille O’Neal  got hurt. Green got more work on the block in New York and for a second unit that sometimes struggled to run a functioning offense that would be a positive development.
Rivers also hinted at a bigger role for Green in the next round. “The other fifth guy [with the starters] is Jeff Green,” Rivers said. “That may be our biggest plus of all the groups, but we just haven’t used it a lot.”
SHAQ UPDATE: O’Neal didn’t practice on Wednesday and he won’t practice Thursday either. The Celtics are targeting Friday as a possible date, but as with all things Shaq, that is subject to change. “We hope he practices [Friday],” Rivers said. “But we don’t know that. We’ll see.”
Everyone else was on the floor at the start of practice, which was closed to the press.
STAYING IN RHYTHM: Everyone knows the Celtics play better with rest, but is there such a thing as too much? Assuming they play again on Sunday that would be a full week between games for the Celtics. They were 1-3 in the playoffs last season with three or more days between games.
“There’s nothing you can do about it,” Rivers said. “It’s not like we can say, ‘Hey listen we want to start now,’ so let’s take advantage of what we have.”
Rivers called this week a mini training camp, but there’s no doubt they don’t want to stray too far from what made them successful against the Knicks, especially the last two games offensively. “When we run our stuff right defensively and offensively we tend to not turn the ball over and we tend to rebound better,” Rivers said.
RUN RONDO RUN: While no one would come out and say it before the series becomes official, Rajon Rondo  will be one of the most scrutinized players in a showdown series with the Heat. He is the one obvious advantage the Celtics have from a personnel standpoint. He showed in the Knicks series that he can kick it up a gear and play with the kind of speed the Celtics need from him.
“It’s night and day when you see it,” Ray Allen  said. “When he’s out there and he’s going and he’s got the energy, he doesn’t care 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.”
Still, the Celtics emphasized that all four of their star players are tied together.
“Rondo’s key for us but all of them are,” Rivers said. “If Rondo’s playing well and Ray is not playing well then we struggle. If Ray is playing well and Paul [Pierce ] or Kevin [Garnett ] struggle then we struggle. It’s not just one guy. This really is a team that is pretty much tied together and each guy has to carry his own load.”