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The Boston Celtics weren't fooled when they swept their playoff series. They knew they still had plenty of improvements to make.

Fortunately, they have time — and lots of it.

So it was back to basics, to some extent, when they practiced Wednesday after two days off and before that night's game in which a Miami win over the Philadelphia 76ers would move the Heat into Round 2 against the Celtics.

While waiting, coach Doc Rivers' team focused on itself.

"We get a chance to work on our stuff, very similar to training camp," he said. "When you start in camp, you really don't have an opponent. You're really just trying to work on all your stuff and we have an opportunity to do that, with rest. So, that's good."

The Celtics finished off the Knicks in four games, concluding with a 101-89 win in New York last Sunday. But they needed last-minute baskets to win each of the first two games and let a 23-point lead shrink to four in the fourth quarter of the finale.

The second unit struggled early in the series, then showed improvement. There were other positive signs.

"It's great to see us play that well on the road," Rivers said. "Game 3 was terrific. Game 4 we started out great and then kind of let up a little bit, in my opinion, and it was great to see us gather ourselves on the road with a team that cut it to four. So, those are good signs."

But the Knicks missed two of their best three players for much of the series. Chauncey Billups sat out the last three games with a strained tendon in his left knee and Amare Stoudemire was limited by a pulled back muscle in those games.

"As much as we won four in a row, it's still a grind," Ray Allen said.

Celtics center Shaquille O'Neal won't practice until Saturday, at the earliest, Rivers said. He has played just 5 minutes, 29 seconds since Feb. 1 because of right leg problems that kept him out of the first round.

The Heat's Big Three are healthy.

And Rivers expected to face LeBron James, Dwyane Wade and Chris Bosh — not the 76ers — in the next round.

"Clearly, you look in that direction," Rivers said with the Heat holding a 3-1 lead before Wednesday's game, "but you do prep work for both. But, really, for us ... we just have to get to doing our defense better."

The earliest the next series can start is Sunday. So even though Rivers gave his players two days off, several gathered together to work out and play 3-on-3 games.

"Obviously, you watch the games and you'd like to be out there playing," Allen said, "but it's something else to have rest this time of year. I don't think anybody's tired. It's just always good to have rest."

The Celtics allowed the fewest points this season, but Rivers issues repeated reminders that good offense starts with stingy defense that allows his team to run, with speedy Rajon Rondo leading the charge.

Against the Knicks, Rondo regained his attacking style that was lacking late in the season. He averaged 19 points, 12 assists and 7.3 rebounds, second only to Kevin Garnett's 11.3.

The long layoff gives players acquired in late February a chance to fit better into the flow. Rivers simplified the plays to get them more involved and singled out Jeff Green as one who has showed progress.

"We're just trying to build a rhythm for ourselves," said Glen Davis, who finished fourth in this season's Sixth Man voting. "You aren't always going to be able to score points. You just have got to play defense, play hard."

That's what Jermaine O'Neal has done.

He underwent knee surgery and played just 24 regular-season games. But he was back for seven of the last nine. In the playoffs, he started at center and blocked 10 shots in four games.

"I feel really good defensively," he said. "Offensively, I think my comfort zone with being out there with the guys and taking shots and getting an opportunity I think that's coming around, too. ... I feel like I still can build off where I left off in the New York series."

Rivers hopes the entire team can. But he sees the playoff field as a wide-open race to the title.

"I've been saying it all year," he said, "but, fortunately, we're in the field."