CHAPEL HILL, N.C. – The young man's big shadow was cast all over Saturday's game between No. 4 Duke and No. 3 North Carolina: From the pregame hype that always accompanies a game between two of sports' greatest rivals, to the in-game analysis that noted how thin the Blue Devils looked down low, to the postgame breakdown, where the main player everyone wanted to hear about was the guy who hadn't played a basketball game in 23 days.

Zion Williamson is the story that has consumed college basketball since well before the first night of the season. There are 353 teams in Division I college basketball, and there are nearly 5,000 players, but there is only one college basketball player who can consume a sporting public's imagination. He's the unicorn college basketball player who not only has become a household sports name but has already morphed into first-name-only status. 

Whether it was the viral video of Zion dunking from the free-throw line at a Duke practice in August, or the 28-point, seven-rebound performance with several superhuman dunks on the first night of the college season that had us wondering whether this team could go 40-0, to the night that President Obama gaped at him courtside at Cameron Indoor Stadium when Zion blew out his shoe and injured his knee just seconds into the first Duke-UNC game, to now, when he's just doing a little shimmy on the bench during the pregame hype song before taking a seat while wear a black Duke polo instead of a black Duke jersey, this season is about one thing: Zion, Zion, Zion.

North Carolina's 79-70 win on Saturday night was a dominating display of what it does best: Get out in transition, push the pace, bang home threes, crash the boards, spread the scoring among its one-and-done likely lottery picks (Coby White, Nassir Little) and senior veterans (Cameron Johnson, Luke Maye, Kenny Williams). If the past seven weeks, during which North Carolina has gone 14-1 during ACC play, hadn't already established this fact, the Tar Heels ought to be a No. 1 seed in the NCAA Tournament, and they ought to be considered not just a team that's capable of making the Final Four but a team that should be one of the favorites to make it. Roy Williams' teams simply get great by the time March comes around.

Zion Williamson was in street clothes as a Duke player for perhaps the last time Saturday. Getty Images

But what America cared about more Saturday night at the Dean Dome had to do with the losing team, and this narrative came into full relief just minutes into the game.

A little more than two minutes after tip, Duke sophomore guard Alex O'Connell clanged a 3-pointer off the rim. The ball bounced to North Carolina senior Kenny Williams, who – the Tar Heels being the Tar Heels, one of the fastest-paced teams in the nation – threw the ball ahead in transition to a streaking Garrison Brooks.

As Brooks rose up toward the rim, and as nearly 22,000 strong at the Dean E. Smith Center bubbled in anticipation, Marques Bolden, the big, brawny Duke junior who was trailing a half-step behind, jumped to try and contest the layup. Brooks and Bolden collided mid-air, and then Bolden landed funny on his left foot, slamming into the stanchion. Immediately, with the type of reaction that gets a trainer off the bench in a hurry, Bolden grabbed his knee. He squirmed on the floor in pain. The Carolina crowd hushed as trainers and managers formed a circle around Bolden. After a few minutes, he was helped off the floor by two teammates. The immediate fear was a torn ACL; it turned out to be well short of that, thank God, a strained MCL.

But it was still enough to knock Bolden out of the game, which left Duke one more player short on an already-shortened rotation. Duke had a 40-38 lead at halftime, and Duke coach Mike Krzyzewski praised his team afterward for continuing to fight, but that moment when Bolden went down felt like the moment that the game became Carolina's to lose.

This season, with such a short bench and a team that's so reliant on freshmen, Duke simply doesn't have any margin for injury at all.

Freshman Tre Jones played all 40 minutes, and told me afterward that fatigue played a part in Carolina dominating Duke in the second half. Freshman RJ Barrett played 38 minutes despite foul trouble that plagued him all game; freshman Cam Reddish played 39 minutes.

The shot distribution? Ugh. Reddish took 23 shots while Barrett took 27; that means 50 of Duke's 73 shot attempts were taken by two players. That's nearly 70 percent of their shots.

That's also why Coach K, before he took questions, before he broke down how Carolina swept both games against Duke for the first time in a decade, before he congratulated Carolina's four-year players on their Senior Night, he spoke about the big man in the Duke polo shirt whose biggest contribution on Saturday night was being a loud, smiling cheerleader for his teammates.

"We've just had some what I call 'combat injuries' – not getting hurt in practice or sick or whatever, but they're playing hard," Coach K said afterward. "I think we'll get Zion back for Thursday (in the ACC Tournament). He had worked out this morning. Again, no contact, but Monday there will be. And hopefully we'll get a couple good days of practice where he can play five-on-five and then see how that goes. The way he looks right now, I think it's just a matter of getting in shape, getting in game shape, and going forward."

Here's the truth about this Duke team: Without Zion, they've been fine. Not really good, but an inconsistent sort of good. Coach K freely admitted as much on Saturday:  "It's not at the level that's needed to win a championship," he said. "In order to win a championship, you have to be outstanding."

With healthy Zion, this team, with all its warts – a lack of depth, a lack of experience, 3-point shooting that ranks among the nation's worst – is outstanding. They're the hands-down favorite to win it all. That team is the team that overcaffeinated pundits were speculating a few months ago as a team that could go out and beat an NBA team. But that team is only that team if Zion is back, and if Zion is 100 percent.

It doesn't matter if it's a preseason practice or a dominating performance on national television, whether he's dancing on the sideline to House of Pain's "Jump Around" or whether he's testing out that healing knee in a full-contact practice to work his way back to game shape, whether he truly does return to Duke this season – Coach K has zero doubt that he will – or whether he takes the advice of so many outsiders and saves himself and his body for June's NBA Draft. There will always be one truth about this college basketball season: It's all about Zion.