NEW YORK — Let us check now on the wildly talented and chronically overlooked men we might call the Best Young Underlings. They have tender ages and gaudy rankings. They also dwell in the overshadowed spaces just beneath the big three — sorry, Big Three. That means they operate beneath one of the most impenetrable ceilings in the history of human competition.

They’re the ones primed to break through to the top someday when Roger Federer, 38, Rafael Nadal, 33, and Novak Djokovic, 32, fade away, which, given the evidence of recent years, appears it will happen in the mid-century, around the time the Big Three finally become septuagenarians.

This U.S. Open isn’t all that far underway, and already they’re down to two underlings who might topple the stubborn, stubborn order: a 6-foot-6 guy who might get to 200 pounds if he ate a few cupcakes (No. 6 Alexander Zverev of Germany) and a 6-6 guy who might get to 200 pounds if he ate a few hundred cupcakes (No. 5 Daniil Medvedev of Russia).

A whole batch of underlings has departed.

Fourth-ranked Dominic Thiem of Austria, 25, who unthinkably snared finalist spots from the Big Three during the past two French Opens before taking the kind of drubbing only Nadal can administer, has departed. It wasn’t his fault. He had a virus that forced his withdrawal from the Cincinnati hard-court tuneup. He tried here because you never know.

“But it was not the real me there on the court,” he said of his 6-4, 3-6, 6-3, 6-2, first-round loss to No. 87 Thomas Fabbiano of Italy.

Eighth-ranked Stefanos Tsitsipas of Greece, 21, who reached the Australian Open semifinals and beat Federer along the way before taking the kind of drubbing only Nadal can administer, has departed. After his 6-4, 6-7 (7-5), 7-6 (9-7), 7-5, first-round loss to No. 43 Andrey Rublev, who looks like a Best Underling in the making, Tsitsipas said one of those things that could make you admire the Big Three all the more.

He described the tour life rather evocatively.

“I feel like I’m doing the same thing over and over again, and my brain can’t really take it anymore,” he said at age 21. “I feel like I’m doing the same routines on the court, the same execution the same — I mean, same strategies and everything. And I feel like my mind is just — I don’t feel inspired. I play out on the court, and I don’t feel like I’m chasing something.”

No. 9 Karen Khachanov of Russia, 23, who reached the French Open quarterfinals, has departed, falling to a 216th-ranked player who has been No. 25, Vasek Pospisil of mighty Canada, in five sets, in the first round. No. 12 Borna Coric of Croatia, 22, withdrew before the second round with a rebellious back. Much-awaited No. 19 Felix Auger-Aliassime, 19, played a much-anticipated, all-Canadian, first-round match against No. 33 Denis Shapovalov, which Canadian women’s budding star Bianca Andreescu called “a popcorn match.”

It fizzled. Shapovalov won, 6-1, 6-1, 6-4, and Auger-Aliassime said: “I don’t even know what my emotions are regarding that match. I don’t know if I should be frustrated, sad. I’m not sure. Yeah, to be honest, about the game, I couldn’t figure out really what to do.”

Asked about injuries, he said, “No, I’m fine.”

Among the hard chargers at the impossible ceiling, that leaves Medvedev, 23, and Zverev, 22. Medvedev has been the shooting star of the summer, with a 14-2 record in reaching finals in Washington and Montreal and winning Cincinnati. Zverev has been on court again with Frances Tiafoe, the marvel of College Park, ranked 45th at age 21.

Friends since they were wee sprites if ever they were, Zverev and Tiafoe had a big hug on Thursday, just after they tussled and tussled until Zverev won, 6-3, 3-6, 6-2, 2-6, 6-3. Zverev, who reached the past two French Open quarterfinals, found his way to his second straight U.S. Open third round.

But it’s rough out there, and whereas Zverev breezed through Tiafoe when they met at the 2017 Wimbledon, Tiafoe looked at his improvement and his Australian Open quarterfinal and said: “It’s night and day. Different player, different person. I mean, yeah, I mean, obviously I’ve had a ton of success since then. Yeah, I mean, it’s night and day. Obviously the outcomes showed it. Yeah, I mean, I had a ton of chances today.”

So Zverev moved along, if unevenly, and that leaves Medvedev as the leading candidate for upheaval should anyone in the world wish to see the Big Three upended, which apparently no one does.

Medvedev has gone through two rounds in seven sets after a summer of which he said, “I was making my opponents doubt a lot what they should do to beat me, and I lost just two matches” — to Nadal and Nick Kyrgios, the Citi Open champion seeded 28th here. Over on the grandstand in the corner of the premises with the jets to LaGuardia Airport visible nearby, he overcame what appeared to be some wretched cramps Thursday in his 6-3, 7-5, 5-7, 6-3 win over Hugo Dellien of Bolivia. “Cramp is not an injury,” he reminded cheerily and hopefully.

He also said: “Of course, as everybody says, before the tournament I was one of the favorites. Probably unconsciously I was looking in the second week, at the draw. As I said, I’m trying to convince myself to look at match by match.”

The best of the Best Underlings at the moment is an affable guy in his 12th Grand Slam with one visit to a fourth round (2019 Australian Open) so far. “Well, look,” Djokovic said after Medvedev beat him in Cincinnati. “You know, he deserves to be in the mix, certainly, with all his results. He’s working his way to top five of the world. He’s definitely one of the best players in the world at this moment. He deserves to be in the contention for the championship in New York. But again, it’s best of five. It’s two weeks. It’s a Grand Slam. It’s a different environment, different experience. It just takes, you know, much more, I think, than just your game. I think it takes patience and ability to know how to deal with all the off-court things, the importance of a Slam.”

And Medvedev himself said: “I always say at this moment of my career I haven’t even been in the quarters of a Slam yet. So that’s the first step to make, and if I make this step, then I can talk about bigger goals and bigger achievements.”

And while Medvedev did look heady, the eternal ceiling did look hard.

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