It has been four years since the ATP announced the inauguration of the Next Gen ATP Finals, an event for the best under-21 players in the world.
Although Hyun Chung of South Korea won the title, the qualifiers for the first event in 2017 included Alexander Zverev, Daniil Medvedev, Andrey Rublev, Denis Shapovalov and Karen Khachanov, while Stefanos Tsitsipas was a substitute.
On Monday, the US Open will begin with five of the six players in the top 10. The next generation of rising stars is not just coming, they are already here.
And yet, there is still a problem. Since Roger Federer won his first Slam title at Wimbledon in 2003, 60 of the 71 Slam events have been won by the Swiss, Rafael Nadal or Novak Djokovic.
Andy Murray and Stan Wawrinka briefly choked with three Slam victories, but since Wawrinka won the US Open in 2016, the only win by a non-big-three player was at last year's US Open, When Dominic Thiem won his first slam.
World No. 1 Djokovic is a strong contender to win this year's US Open, which would coincidentally make him the first person since Rod Laver in 1969 to win all four majors in a single year. But the feeling is growing that the baton is not far away. Federer is 40 and facing another rehabilitation after knee surgery, while Nadal has a leg injury that will keep him out for the rest of the year.
The fact that there's a bunch of players around the same level is helping give the pretenders the confidence that they can eventually make that slam a success.
"Maybe [we] all want to be the first to make it," Medvedev told reporters at Flushing Meadows on the eve of the Open. "Actually Thiem is the first, if we can call it NextGen, which we're not now, but we were kind of in this group, he was the first to do that last year. Only Novak of the big three is here, Which is definitely going to the Grand Slam.
"Stefanos was in the final at Roland Garros, two sets [on Djokovic]. I was in the final in Australia, not in the two set ups, but still in the final. We're going to try to get (Djokovic).
"It's to be the first of these young guys to win a competition slam... I think everybody wants to do it."
For many years, the biggest issue always seemed to be that in order to win a Grand Slam, the probability that a young player would have to beat at least one, and sometimes two out of three, to win a major title.
Wawrinka did so in 2014 when he won the Australian Open and Roland-Garros in 2015, but the youngster has fallen short, sometimes managing a big win but then finding another obstacle in his way .
Tsitsipas beat Federer only to reach his first Grand Slam semi-final in Australia in 2017 to Nadal, and was overhauled by Djokovic at Roland-Garros this year. Medvedev was stopped by Nadal in the 2019 US Open final and by Djokovic in Australia in February.
This time the road to the Grand Slam final is a little less complicated.
Zverev, who won the Olympics in Cincinnati and most recently the Western and Southern tournaments, knows that he and the others are close.
"We all miss them, we all love to play them forever," Zverev said of the big three. "(But) at some point he will have to retire.
“I think the Cincinnati tournament and other tournaments this year also showed that the competition and rivalry that we have with young people – top four or top five guys with Medvedev, Tsitsipas, myself, Rublev and (Matteo) Berrettini, We're having great fights, we're having very fun matches.
Medvedev, Zverev, Tsitsipas and Beretini (at this year's Wimbledon) have all made it to the Grand Slam finals. Medvedev, Zverev and Tsitsipas have all won the ATP Finals. His time may finally be here.
"I'm two points away from here (from the title) last year," Zverev said. "I'm very happy to be back here, because now I feel like I can go on that court and prove to myself whether I've been better than last year, that's exactly what happened. I am playing well. Tennis this year.
"Top three guys, they've been dominating for the last 15 or 20 years. We may never see it again. Don't expect this group of people to be the next Djokovic, Federer and Nadal. I don't think there are four of us Going to win 20 Grand Slams in the next 15 years. It's not like that."
Zverev is confident about the future but knows the big three have established high bars.
"I think we're going to divide them among us. But the dominance of those people is something you probably only see once in a lifetime. We all, we're on that kind of path. We aim for the same kind of goals. Share and aspirations.
"I personally believe that we all have a good game to play in order to win a Grand Slam title. It is important that we are able to perform in tournaments like this to the level of tennis that our generation's tennis has brought." As possible to represent. In the best possible way."
Djokovic remains the standard, but the pack is closing in.