Holger Rune has his moment, but Novak Djokovic wins in four sets, leaving him six wins away from tennis history

You Should Know: Jon Wertheim on the surprising recent histories of Novak Djokovic and Holger Rune

NEW YORK—Facing a player half your age: It’s a phenomenon that Roger Federer and the Williams sisters have been dealing with for a few years, and now it’s Novak Djokovic’s turn. On Tuesday night, the 34-year-old world No. 1 began his quest for a calendar-year Grand Slam against 18-year-old Holger Rune of Denmark.

If anything, Rune looked and acted even younger than that. Full of energy for his first night-session match at the US Open, the muscular teenager leaped and bounded and swung for the fences. Waiting to return serve, he couldn’t stop swinging his upper body back and forth. Rune is a former No. 1 junior, and this won’t be the last time we see him in Arthur Ashe Stadium.

Naturally, the crowd in New York, which loves effort, novelty and the smell of an upset, took to Rune right away. Djokovic’s attempt to make history this year didn’t turn this crowd in his favor on this night. The fans roared for every Rune winner, exploded when he broke Djokovic’s serve with a forehand pass, and stood to applaud when he won the second set. They chanted “Ruuune,” like he was “Bruuuce” Springsteen. Djokovic thought they were booing.

“It was not ideal atmosphere for me, to tell you that,” Djokovic said. “But I’ve been in these particular atmospheres before, so I knew how to handle it.”

Whether or not the crowd had an effect, Djokovic’s performance veered wildly from the first set to the second. He was sharp and aggressive to start, going after his forehand and backhand with force, and wasting no time moving in to finish points at net.

“My side, I started great,” he said. “Played a really, really good first set.”

To the surprise of everyone, Djokovic’s momentum flagged, twice, in the second set. First, Rune found his range and broke to go up 3-0. Then, after Djokovic broke back twice to go up 4-3, Djokovic’s level dipped and Rune took heart again. While the teen jumped around and belted winners, the veteran put his head down and surrendered the initiative. At 4-3, Djokovic tried two big second serves, and double faulted both times.

“I don’t know, I was 4-3 serving in the second set. Everything was working well, but then I just lost the first serve,” Djokovic said. “Very low percentage of first serves.”

“Credit to him for fighting. He had the crowd behind him. It was tough to play in my first match…Still you get nerves. You still are feeling a little bit rusty at the beginning.”

In the end, Rune may have bounced around a little too much. He cramped in the third set, and struggled to move after that. Djokovic made quick work from there to win 6-1, 6-7 (5), 6-2, 6-1. Yet Rune won the crowd’s respect a second time by refusing to retire, even as walked in obvious pain between every point.

The relevant questions now is: Was Djokovic’s second-set dip a reason for concern going forward?

I’ll start by saying that the crowd likely won’t be an obstacle. By now, Djokovic knows how to block out an unsupportive audience, or even use one to his advantage. As for that dropped set to Rune, Djokovic also dropped one in his first-round match at Wimbledon, against Jack Draper, and then didn’t lose another until the final. But there have been a couple other times this year—the Lorenzo Musetti match at Roland Garros comes to mind—when he has had trouble fully focusing in the early going against a player he knows he should beat. If that were to happen against a stronger opponent than Rune in New York, things could get more complicated than he would like.

What’s safe to say at this point is that Djokovic knows what he’s doing in best-of-five-set matches better than anyone else in the draw. And as he said tonight, he also knows Ashe Stadium better than anyone he’s going to face. They may not cheer for him in there, but he’s come too far to let that stop him now.