WALTHAM, Mass. — Long after practice ended, Ray Allen was still on the court firing up jumpers.

He was even making most of them.

That overtime work Monday showed that, like his Celtics teammates, he had plenty of energy left after two intense seven-game series. And the usually smooth shooter was regaining his rhythm.

Whether the Pistons still have theirs after a six-day layoff will become evident in Tuesday night's opener of the Eastern Conference finals.

"I would rather have the rhythm" of regular competition than extra rest, Allen said, "because (with) the rhythm you don't have to guess from one day to the next" how you'll play.

Boston has played three games since Detroit won its conference semifinal in five games against Orlando last Tuesday. The Celtics advanced with a 97-92 victory over Cleveland on Sunday in which Paul Pierce scored 41 points. Allen had just four and averaged only 9.3 points on 32.8 percent shooting in the series, far below his regular-season performance.

If he starts scoring again, he would give the Celtics their usual three main scoring options, joining Kevin Garnett and Pierce, to go against a Pistons team that has a much more balanced offense than the Cavaliers, who lost Sunday despite 45 points from LeBron James, and Atlanta, Boston's first-round opponent.

"It's the exact opposite," Celtics coach Doc Rivers said. "You go from Cleveland and Atlanta in a lot of ways with Joe Johnson, where you focus on double-teaming, to playing a team that all the guys in the starting lineup are capable of having good nights."

The matchup with Detroit is what Rivers and many others expected.

Both are deep teams with outstanding defenses. The Celtics had the NBA's best record (66-16), earning homecourt advantage throughout the playoffs, and the Pistons were second best (59-23). The Celtics have plenty of players with playoff experience, though not as teammates, and the Pistons are in the conference finals for the sixth straight season.

Chauncey Billups, Richard Hamilton and Tayshaun Prince have been on all of those teams. Rasheed Wallace is in his fifth year with the Pistons. But they last won the NBA title in 2004, then lost to San Antonio the next year.

Pierce, Garnett and Allen are each in the conference finals for only the second time in their careers.

"I think we probably will be the underdog," Pierce said, "knowing that Detroit has been there. They won a championship with this group and are used to going to the Eastern Conference finals and this is just our first trip."

Still, the Pistons are hungry to get back to the finals for the first time since 2005.

"It's only been three years, but it seems like forever," Hamilton said. "We feel ... we haven't been there in a long time. So we want to do everything possible to get right back to where we were at."

Boston was 8-0 at home but 0-6 on the road in the first two rounds. The Pistons have three road wins in this postseason.

The Pistons didn't have homecourt advantage the last two times they won the conference finals in 2004 and 2005. Game 2 this week will be Thursday night in Boston, with the next two games Saturday and Monday in Detroit.

"I try not to even put any emphasis on it," Allen said. "I think you approach the situation (as) we're going out here to win a game, regardless of where we are."

Detroit also was solid on the road, going 25-16 in the regular season, with one of those wins in Boston. The Celtics were 35-6 at home.

"That's a big plus for us that we have won there in a season that they won most of their home games," Billups said. "We know we're a great road team in anybody's building and that's to our advantage. Our whole mind-set is to go there and win Game 1."

If they do, the Celtics would be in a big, early hole. The best they could get, then, would be a split before the series shifts to The Palace, where the Pistons were 34-7.

But that wasn't on the Celtics' minds Monday when they went through a light workout after Sunday's draining game that wasn't decided until the final minute.

On Monday, Pierce and his teammates awoke with a rare feeling for the franchise. They were in the conference finals for the first time in six years.

"When you're waking up you notice that the sun's been out. It's been warm outside," Pierce said. "It's very rare that you're playing in the Eastern Conference that you're still playing when it's 70 degrees, so you know you've gone pretty far in the playoffs and I think some guys wake up and say, 'hey, we're still playing,' and they get excited about it."

And the Pistons don't expect to take comfort in the fact that the Celtics were pushed to the limit in both series.

"We've got to go in and play this team like they swept everybody," guard Lindsey Hunter said. "They were the best team in the NBA. They didn't accomplish that by chance. We'll come in as though they're fresh as we are."

Besides, overcoming all the setbacks of a seven-game series should harden the Celtics for what's ahead of them.

"We've learned a lot about each other. It's good for us because as a team this is our first time together," Allen said. "Our valleys that we're going through, seven games, adversity on the road. All that stuff that people say is a reason why we won't win, it's a reason why we will win."