Jayson Tatum and Jaylen Brown shone at the start of the Boston Celtics' 107-105 win against the Miami Heat on Wednesday, but the most encouraging sign for one of the NBA's elite young duos was the way they finished.

Well, technically, rookie Payton Pritchard was the one who iced a game that got a lot dicier than it should have in the final minute. But it was Tatum and Brown who followed a first-quarter barrage with an even more consequential closing run.

That late burst? That was what the Celtics should value most because it was yet another step forward for a pair of teammates who have proved they can start games and careers impressively but have yet to show they can finish in a grander sense.

Tatum and Brown blitzed Miami early, scoring 15 of Boston's first 21 points while showcasing the growth that has made them one of the season's most intriguing stories.

Tatum came out with a mind to score, bullying Duncan Robinson on a drive for his first bucket and then splashing a pair of threes in the opening minutes. Brown, not to be outdone, continued his mid-range mastery and showed off his development as an on-ball threat with a smooth pull-up three.

Brown also handed out four early assists while Tatum dimed up teammates just as adeptly in a thoroughly impressive first quarter.

The two have been fast starters in a much broader sense, both having played major roles in deep playoff runs as rookies.

Brown was in the rotation during the Celtics' surge to the 2017 Eastern Conference Finals, and Tatum joined him a year later when both started in the 2018 run that took them just as far. In all, they've already logged 106 combined playoff games. Those trials by fire forged a pair of young players, giving them an immediate understanding of what it takes to compete at the highest level.

Given that early plunge into the deep end, it cannot register as a surprise that they've developed into stars (with plenty more room to grow) this quickly. Tatum is 22 and already an All-NBA performer. Brown, showing more clearly than ever that he's too good to be considered a Robin to Tatum's Batman, continues to evolve at age 24.

Coming into Wednesday's win, they'd already registered historic production for a franchise that has featured more than its share of impressive young tandems.

Their work grades out just as well in a league-wide context.

These two are unique among NBA pairs for reasons that go beyond their early-season numbers and early-career success. There are plenty of homegrown duos out there: Stephen Curry and Draymond Green, Joel Embiid and Ben Simmons, Damian Lillard and CJ McCollum, Donovan Mitchell and Rudy Gobert, and Nikola Jokic and Jamal Murray all come to mind.

But none of those pairs feature oversized two-way wings, the league's most valuable commodity.

That distinction is a blessing for Boston, but it comes with curses. The Celtics can't just run pick-and-rolls with both players to generate switches or mismatches like, say, the Utah Jazz can with Mitchell and Gobert. And we've too often seen partnerships like this one dissolve because a "my turn, your turn" dynamic develops that sets a ceiling on team success.

Think of Lillard and McCollum or even Kawhi Leonard and Paul George, if we dispense of the homegrown requirement.

The key for the Celtics is that Tatum and Brown are both off-ball threats who are continuing to develop as passers. And with all their shared formative moments in critical playoff games, both understand the necessity of contributing to the game in ways that go beyond scoring.

If you were building a one-two punch designed for postseason success in a lab, you'd put it through the exact developmental trials Tatum and Brown have faced.

None of that mattered to the Heat on Wednesday, of course, as the team that bounced the C's from last year's playoffs wasn't fazed by an early deficit that grew as large as 17 points.

Brown disappeared for most of the second half, going cold from the field and forcing Tatum to take over, which he did with 10 points in the third quarter. That wasn't enough to prevent Miami from battling back and taking a five-point lead with just over four minutes left in the frame.

It was nip and tuck from there until Brown awakened and hit a three to tie it at 95 apiece late in the fourth. Tatum followed that soon after with a trey of his own, after which he set up Brown for another triple that put the Celtics up by eight with 1:53 left to play.

Robinson went off for Miami from there, raining fire as the game devolved into a giant rugby scrum until the buzzer. But the late surge engineered by Boston's stars ultimately held up with, again, Pritchard's clutch tip-in deciding the result.

Maybe that says more about how impressive Tatum and Brown have been—and can be—than anything else.

At 22 and 24, they've accomplished so much, so early, that they're already in a position where success at the very end of it all, a championship, is the only kind that eludes them.