Rajon Rondo and LeBron James will face off again at TD Garden on Sunday. (AP)

The elation was reminiscent of a championship ceremony. The collective relief from the crowd, the exhaustive expressions of the victors and the sour disappointment of the losers were all palpable. The Heat had beaten the Celtics in five games … to advance to the Eastern Conference Finals.

Re-watching the celebration unfold, it becomes extremely difficult to keep the moderate accomplishment in perspective. LeBron James began ”Tebowing” (before “Tebowing” was a thing), Dwayne Wade fell to the floor like Michael Jordan after he won his third NBA title in 1993, and Doc Rivers (who was rumored to be stepping away from coaching after the conclusion of the Celtics’ playoff run) wandered around the floor like a lost puppy.

Needless to say, it felt like something was happening. A coronation of some sort. Presumably, the hoary Celtics would no longer be a threat following the 2010-11 playoffs, and the manner in which James spoke about his adversary in the immediate aftermath was extremely deferential — almost like a eulogy.

“First of all, I want to give a lot of thanks to the Boston Celtics,” James said. “Doc Rivers, that coaching staff, them players — they make [you] fight for everything, you can never take your foot off the gas, you can never take a second off against that team, so a lot of respect for that team.”

However, as James was giving praise and soaking in the moment, Rivers was preparing for his post-game press conference, where he unexpectedly declared he was coming back to coach the next season and beyond.

The Heat would advance to the NBA finals, eventually losing to the Mavericks in six games. Rivers’ decision made ripples, putting a moratorium on the passing of the crown, but most likely flew under the radar in the Heat locker room since they had advanced and the Celtics were going home.

That playoff series featured emotions that seemed elevated beyond the stakes of the individual contest. Regardless of where the two teams stand in the conference rankings, there’s enough star power — one Big Three facing another — to make matchups between the teams an event. And that is part of the allure of the next meeting of the teams on Sunday, when the Heat come to TD Garden to face a Celtics team playing at its highest level this season.

The Here and Now

The Celtics and Heat met once before this season, in the second game coming out of the lockout-shortened training camp, with the Heat beating the Celtics, 115-107, and in the process, staving off a frantic fourth-quarter rally and six 3-pointers from Ray Allen.

That meeting is remembered as the Norris Cole Game. The 23 year-old rookie out of Cleveland State University helped thwart the Celtics’ comeback, scored 20 points on 6-of-8 shooting.

For all intents and purposes, the December 27th match-up in Miami can be dismissed, considering it was the second game of the lockout season, Cole logged 30 minutes (more than 10 above his season average) and the Celtics were without Paul Pierce. On the other hand, the game undoubtedly served as an early reminder that even though the Celtics may not be performing at the same sustained level of competitiveness, they still are a tough out.

These two teams face one another three times in the final 15 games of the season. And if the Celtics fail to hold onto the lead in the Atlantic division, there is a strong possibility they could meet the Heat in a first round match-up as a seven seed. So, with all that possibility hanging in the balance, it is worth taking a peak at the trends going into Sunday’s showdown.

The Celtics’ up-and-down season has been a roller coaster. They come into Sunday having won six of their last seven; they are 14-5 since the All-Star break. The biggest difference when examining the numbers from a team perspective is Boston’s proficiency in scoring. Before the break, the Celtics averaged 89.4 points per game; in the 19 games since, the Green have scored 95.3 points a game.

There are many factors that have contributed to the Celtics revitalized offense. The most obvious change is Kevin Garnett‘s switch to center, which has created match-up problems for slower big-men, thus paying massive dividends for the C’s. In the last 10 games in particular, KG is averaging 19 points (shooting an efficient 54.8 percent) with eight rebounds. More importantly, he’s been far more aggressive in the role — taking three more shot attempts (15.5) than his season average.

In the same stretch, Rajon Rondo has averaged an unbelievable 14.1 assists. Boston is 19-8 in games that Rondo dishes out 10 or more assists. The cerebral point guard has seen his scoring average dip, and he is only attempting nine shots a game. The Celtics may ask him to be more assertive in his game as they face a more difficult schedule in the month of April.

Pierce has played well of late as well. His assists are down since the All-Star break, but that is because he was asked to facilitate more while Rondo was nursing a wrist injury for eight games. The rest of his game, however, has been fantastic. With Rondo back, the captain has gone back to doing what he does best, averaging 21.6 points per game, nearly four more points than his output before the break.

The Heat’s season has unfolded as one would expect — the team’s chemistry congealing after another year with one another, holding the second-best record in the Eastern conference, at times looking dominant, while remaining a favorite to reach the NBA Finals for the second straight year.

Miami boasts an impressive 37-13 record, largely due to their offense, which ranks third in the league with 101 points a game. While the Heat have been virtually unbeatable at home (21-2), their road record is slightly suspect at 16-11. This bodes well for the Celtics as two of the three meetings with Miami will occur in the confines of the Garden.

Additionally, the Celtics’ biggest weakness isn’t necessarily Miami’s greatest strength. The undersized frontcourt of Brandon Bass and Garnett have been dominated on the boards this season. The Celtics rank 30th in total rebounding, but the Heat aren’t much better in the front court. Joel Anthony works hard down low but is 6-foot-9; Chris Bosh is 6-foot-10, but has a slim frame. In short, the Celtics will not be totally exposed against the Heat like they are against many clubs.

Duel on the parquet

Every time James and Pierce face-off at the Garden, Game 7 of the second-round playoff series in ’08 naturally comes to mind. In a memorable clash, Pierce scored 41 points while James countered with 45 in a losing effort. But that was then — four years ago — and this is now.

The two have faced one another nine times since James joined the Heat last season. James has had the upper hand, averaging 28 points to Pierce’s 18. Both players have shot above 45 percent from the field.

At 27 years old, James is entering his prime, and the scary part is he is figuring out how to play a style of basketball that is even more effective than the type he played while winning his two MVP awards. This season he is shooting a higher field goal percentage (53.5 percent), getting involved more down low (averaging over a rebound more a game), and wisely only taking two 3-point field goals a game versus the 3.5 attempts he jacked up last season.

With Allen a game-time decision and Mickael Pietrus out of the lineup, the Truth will need to either score at a higher clip or contain the King for 48 minutes for the Celtics to have a chance.