The inaugural under-21 version of the ATP World Tour Finals starts today in Milan, bringing together emerging stars tipped to rival Rafael Nadal, Andy Murray, Novak Djokovic and Roger Federer.
But a social media storm was whipped up after Sunday's draw ceremony when the players had to choose female models who had the letter 'A' or 'B' hidden on their bodies, to determine the round-robin group in which they would play.
South Korean player Hyeon Chung looked visibly embarrassed as he was asked to pull off a female model's glove with his teeth during an evening designed as a tribute to Milan's famous links with the fashion industry.
"It's unfair and unreasonable we put these guys out there. It wasn't their choice, it's in no way to do with any of the players here tonight," he stepped in to add when the eight players were questioned.
More From This Section
"Disgrace", wrote former women's number one Amelie Mauresmo on her Twitter account, while fellow French player Alize Cornet wrote: "Good job @ATPWorldTour Supposed to be a futurist event right? #backtozero", as Judy Murray, mother of former men's number one Andy Murray, tweeted "awful".
"I've receive a huge amount of mixed response. We're not trying to 'mess with the game of tennis' but to try things that in five to 10 years we might eventually integrate into the sport.
"We want while the sport is in the best place it has ever been to try to look towards innovating for the future.
"These guys are the future and they're going to be here for a long time."
The highest-ranked player in Milan will be Russian Andrey Rublev, ranked 37th, and a winner this year on clay at Umag.
Rublev said he was honoured to be considered among the heirs to Nadal, Federer, Djokovic and Murray.
"These top four guys are something unreal, they are legends, I grew up with them and they are still top. To get close to them you have to put in a lot of work, only time will show."
Khachanov sees a bright future for Russian men who have not held a Grand Slam since Marat Safin won the 2005 Australian Open.
"A lot of players from Russia are here. It's just a new generation, young guys playing together, getting connected," said Khachanov.
Canadian Denis Shapovalov (ranked 51), American Jared Donaldson (55), Croat Borna Coric (48), South Korea's Chung (54) and Italian qualifier Gianluigi Quinzi (306) complete the line-up.
"The US has a rich tradition in tennis greats, there's been a lot of talk of a drought of a Grand Slam winner, just that the game has become more international, looking at this group so many continents are touched," said Donaldson.
For Shapovalov the most difficult change is getting used to the 'no-let rule'. "For me that would be pretty challenging," said the Canadian.
Chung added: "I'm so happy to be part of these great players here. I'm trying to play my best this week."
The top two from each group will progress to the semi- finals, with the final next Saturday determining the best young player in the world and the winner earning $1.2 million (1.03 million euros).