When Miami visits Boston on Sunday, it'll be trying to stay atop the Eastern Conference and extend the NBA's longest current winning streak.

And those will be Miami's secondary goals.

To the Heat, what matters most is finding a way to finally beat the reigning East champions. Miami is 0-2 against Boston this season and lost to the Celtics in the first round of last year's playoffs in a largely one-sided series. After that, Boston ousted LeBron James and the Cleveland Cavaliers as well.

"We just want to see where we're at," Heat guard Dwyane Wade said. "It's not as big as everyone seems to be making it. But it's not another regular-season game."

No, it isn't — not with these stakes.

A Boston win would ensure the Celtics clinch the season-series — and any potential tiebreakers — with Miami, plus move them back on top of the East standings. Miami moved into the East lead on Friday night by winning in Detroit, improving to 39-14 and a half-game clear of the Celtics.

Another win would mean Miami needs only to beat Indiana on Tuesday or Toronto on Wednesday to head into the All-Star break with the East's best mark.

"We're still trying to get better every day," said James, the two-time reigning NBA MVP who is averaging 26.2 points in his first season with the Heat. "We're taking every practice and every regular-season game like it is the playoffs because we can't afford to lose an opportunity to get better."

The teams haven't met since Nov. 11. Boston won 88-80 at home in the NBA season-opener Oct. 26, then prevailed 112-107 in Miami about two weeks later.

"Now we're sitting on top of the East, going into a hostile place where we did not play well the first game of the year," Heat coach Erik Spoelstra said. "We respect who the Boston Celtics are and what they've proven the last 3½ years. So this is what everybody, the fans, the media and everybody out there, this is what they want."

The last time Miami led the East was in the second week of January, and as soon as the Heat reached the top spot, they plummeted. Miami lost four straight, Boston simultaneously won five in a row, and the gap between the two was sizable once again.

It's disappeared rather quickly. Miami brings an eight-game win streak into Sunday, while the Celtics suddenly look vulnerable after losing four of their last seven.

"I don't think they care about that," Spoelstra said. "They have confidence in what they've done. They've proven themselves. I'm sure if they're sitting over there, they feel like they have enough to beat us."

Earlier this season, that was clear.

But after dealing with a slew of early growing pains, the Heat say the team they are now doesn't even compare to the one that faced Boston months ago.

Miami started 9-8, a predictably rocky — though bumpier than some expected — start after finding the best way to have Wade, James, Chris Bosh and a slew of other new faces on the roster together. Two of those eight losses came against the Celtics.

"It took us a little time," Wade said. "And now we're very comfortable in late games and we feel like we should win if the game is close. It's not always going to go that way, but we have that mentality."

Since then, the Heat have posted the NBA's best record, winning 30 of their last 36 games. And in four of those six losses, Miami was without either Bosh, Wade or James because of injury.

Each of Miami's "Big 3" will be in the lineup on Sunday.

"It's going to be a hostile environment," James said. "It's going to be a great game. It's two teams that have the same aspirations, and that's to win the NBA championship. They're the defending Eastern Conference champions and you've got to kind of go through them to get what you want."