BOSTON (AP) — There’s never a good time to play the Cleveland Cavaliers, who finished the regular season with the league’s best record and seem determined to win their first NBA title before LeBron James can leave as a free agent.

“So,” Boston coach Doc Rivers said, “Why not now?”

The Celtics are as healthy as they’ve been all year, and the aging roster isn’t likely to get any fresher as the playoffs wear on. There are three days off before the start of the Eastern Conference semifinals, so they’ll be better rested than usual.

“If you want to win it, you’ve got to play them all anyway at some point,” Rivers said minutes after the Celtics advanced to the second round and before Cleveland had even finished off Chicago. “So, you know, why not now? We’re there, we’ll be waiting; we’ll be ready. And I’m sure they will be.”

The Celtics advanced to the second round of the playoffs with a Game 5 victory over Miami on Tuesday night. Cleveland joined them about an hour later when it dispatched the Chicago Bulls in their fifth game.

The series begins Saturday in Cleveland, with Game 2 on Monday.

The Celtics and Cavaliers last met in the playoffs in the 2008 conference semis, when Paul Pierce dueled with James in Game 7 and Boston went on to win its unprecedented 17th NBA title. The big difference this time is that Cleveland has the home-court advantage in a potential seventh game.

“It’s a great matchup. It’s great for basketball — such a classic series a couple of years ago,” Pierce said. “It’s a huge mountain we going to have to climb, but I think this team is ready to face the test. We are playing as good as basketball we have been playing all season long, and we are ready.”

The Cavaliers won 66 games last year but lost in the conference finals to Orlando — one round after the Magic ousted Boston, which was playing without Kevin Garnett. Cleveland won just 61 games this season but entered the postseason better rested: James sat out the last four games after the top overall seed was clinched.

But the Cleveland star complained about a sore right elbow and shot his final free throw at the end of Tuesday night’s game with his left hand. He compared the pain to banging your funny bone and said he wasn’t concerned, but also said the biggest problem was not knowing the cause.

“I’m healthy,” he said after the game. “I’m ready and we are looking forward to the second round. They (fans) don’t have any reason to panic.”

The Celtics think their injury problems might be behind them.

Garnett is back from the hyperextended right knee that kept him out for 10 games around New Year’s Day; Pierce missed 10 games during the season with knee, foot and thumb problems. Neither has missed a game due to injury since late February, and Rivers has controlled their playing time.

The Celtics went 2-2 against Cleveland in the regular season, and one of the losses was without Pierce.

“You definitely had your doubts at times because the inconsistent play, injuries just seem to be mounting and mounting,” Pierce said. “But the thing that I credit this team about is the mental toughness.”

Heat coach Erik Spoelstra understood that the team he was meeting wasn’t the same one that spent the last two-thirds of the regular season limping into the playoffs with a .500 record.

“With their starting lineup intact they’re 38-18. That seams like a pretty good record to me,” he said Tuesday night after losing to Boston. “They got healthy at the right time. … They understand what the moment is. They’ve had injuries. Everybody discounts that and that’s a big part of the NBA season.”

Spoelstra said as much to Rivers when they talked.

“He said, ‘It was a battle for you to get your team healthy, but I think you’ve finally got a healthy team to coach,'” Rivers recalled after the clincher. “I did feel good about our team because I thought we had good rest going into the playoffs and we were healthy.”

They’ll get more of the same heading into Cleveland.

The NBA will give the teams three days before the opener, and there could be a long wait before the series returns to Boston to guarantee the TV networks a Sunday afternoon game. That’s good news for James but it could be more beneficial to the Celtics Big Three, who are 32, 33, and 34 years old.

“The last two years we’ve gone to Game 7 in the first round, and it can wear on you,” said Ray Allen, who scored 24 points on Tuesday night while covering Dwyane Wade on defense. “It will only be a struggle from here on in.”