BOSTON -- This journey towards being one of the NBA's elite teams is not for the faint of heart.
It requires having a Teflon-tough will to win, the kind that allows you to come from 26 points down against the second-best team in the NBA; the kind that involves knocking off the defending champ twice in the same calendar year – something no team in the East other than the Boston Celtics can lay claim to accomplishing.
Despite the Celtics' success against the best, the latest mile-marker in their journey -- the Cleveland Cavaliers -- may prove to be the toughest for them to race past.
Among the league's top-tier teams, no one has owned the Celts the way Cleveland has.
In the regular season, Cleveland has won 9 of the last 11 matchups.
The playoffs have been just as tough on Boston, with the Celtics season coming to an end at the hands of the Cavs in two of the last three seasons. And in those two playoff series, Boston has a 1-8 record.
"They got a guy that's probably leading the charge for MVP in LeBron [James]," said Celtics coach Brad Stevens. "They're the team to beat; everybody knows that. We can all speculate through the season all we want to, but they've been the class of the East."
But the Celtics have closed that gap this season and seem on paper at least, well-positioned to take that first step towards making this a more competitive series.
Al Horford understands the Cavs are the team that Boston and every team in the East for that matter, is chasing for that top spot.
"That's fair to say," Horford said. "They're the ones that have won the East all these years in a row. We know what we have. It'll be a good game for us to come out and play the right way and grow as a team. I'm just excited about the challenge."
Even with the game being in the comfortable confines of the TD Garden, Boston will have its hands full in trying to knock off the defending Eastern Conference champions.
But then again, this season has been filled with challenges that for the most part Boston has met head-on and found a way to not just compete but emerge victorious.
-- On Nov. 16, Boston trailed by 17 points only to rally for a 92-88 win over Golden State.
-- Just four days prior to the win over the Warriors, Boston held off the Toronto Raptors 95-94, a team that had beaten Boston 11 of their previous 16 meetings.
-- Even San Antonio, which came into the season having beaten Boston 11 straight times, came up short, 108-94 on Oct. 30, at the TD Garden this season.
Second-year wing Jaylen Brown is well aware of the historical struggles Boston has had with some teams like the Cavs.
But he knows that this team, with so much youth and so many new faces, isn't the least bit concerned with or consumed by events of the past.
"It's a whole new team now," Brown said. "Same coaching staff but whole new players. Most of them are players, are young guys. I don't think we have anything nostalgic built up. Everyone can come in and just play freely. That's the beauty of it. That's where we have our edge; come out, play freely, play aggressively."
Said Al Horford: "It's gonna be a fun game tomorrow. Two teams really getting after it, two of the better teams in the league. It's gonna be fun."