The inaugural Next Gen Finals starts on Tuesday in Milan and features the top seven 21-and-under players in the rankings plus one Italian wild card.
Here is the possible future of men's tennis:
ANDREY RUBLEV
This has been a breakthrough year for Rublev, who won his first ATP title and reached the U.S. Open quarterfinals. Rublev was only in the Umag Open in Croatia as a lucky loser, after losing in qualifying, but he went on to the final and beat Paolo Lorenzi in straight sets in July.
On his way to the quarterfinals at Flushing Meadows, Rublev upset two top-10 seeds before losing to eventual champion Rafael Nadal.
Rublev, who was 19 at the time, became the youngest player to reach the U.S. Open quarterfinals since Andy Roddick in 2001.
The Russian tennis player reached a career-high ranking of 35, though he's at 37 this week.
KAREN KHACHANOV
The only one of the finalists to break into the top 30 — 29 in August. He has dropped to 45th but Khachanov has made great strides since winning his first title at the 2016 Chengdu Open. Khachanov reached five quarterfinals this year, and the semifinals in Halle, where he narrowly lost to Roger Federer.
The Russian also reached the fourth round at the French Open and the third round at Wimbledon.
At 1.97 meters (6-foot-6), Khachanov is physically strong and his forehand is already among the biggest on the tour.
DENIS SHAPOVALOV
At 18, Shapovalov is the youngest player at the finals, and 2017 has been full of highs and lows for the Canadian.
Shapovalov hit the headlines for the wrong reasons in February when he lost the deciding rubber of Canada's Davis Cup tie against Britain by disqualification, after hitting umpire Arnaud Gabas in the eye when he whacked a ball in frustration after dropping serve.
However, Shapovalov pushed on from there and in August became the youngest player ever to reach an ATP Masters 1000 semifinal, at the Rogers Cup, beating Nadal on the way.
He also became the youngest player to reach the fourth round of the U.S. Open since Michael Chang in 1989.
Shapovalov reached a career-high ranking of 49 in October, although he has slipped back two places.
BORNA CORIC
Not many 20-year-olds can boast about having beaten Nadal and Andy Murray, but Coric can. If he wants to.
Coric burst onto the scene in October 2014 when he beat Nadal to reach the semifinals of the Swiss Indoors, launching him into the top 100 and making him the youngest player to break that barrier since Nadal in 2003.
The Croatian has endured ups and downs since then before beating Nadal again in 2016 in straight sets.
Coric's previous season was prematurely ended by knee surgery but he returned to win his first ATP title at the Grand Prix Hassan II in April and beat Murray at the Madrid Open the following month.
Coric, ranked as high as 33, has slipped to 48th.
JARED DONALDSON
Donaldson broke into the top 100 after the 2016 U.S. Open, where he reached the third round beating 12th-seeded David Goffin.
The American has raced up the rankings this year.
Donaldson started 2017 ranked 105th but reached a career-high 50th last month. He enters the tournament at 55.
Unlike most American players, who generally are more proficient on the serving side of the game, Donaldson's strength is in his return game. He is rated higher in that category than the likes of Stan Wawrinka, Juan Martin del Potro, and Jo-Wilfried Tsonga.
HYEON CHUNG
Chung is instantly recognizable on the court by his prescription sports glasses which have become his trademark.
In fact, the South Korean took up tennis only to maintain his eyesight after a doctor suggested that looking at the colour green would help.
Chung was awarded the year-end ATP most improved player award for 2015 after climbing 100 places to 51st in the rankings.
He had his best result at a Grand Slam this year when he made the third round of the French Open.
That helped push him up to 44 in the rankings, although he has slipped to 54.
DANIIL MEDVEDEV
Rarely can a second-round loser have made such an impact at a Grand Slam. But Medvedev hit the headlines for good and bad at Wimbledon.
Medvedev upset No. 3-ranked Wawrinka in his first match but the second round saw him heavily fined for unsportsmanlike conduct. After losing to Ruben Bemelmans, Medvedev opened his wallet and threw some coins at the foot of the umpire's chair following his defeat.
Medvedev, who is ranked 65th, down from 48th, has since been seeing a psychologist.
GIANLUIGI QUINZI
Italian hopes were pinned on Quinzi when he became junior world no. 1 in 2013 and went on to win Junior Wimbledon, beating Chung in the final.
However, Quinzi buckled under the expectation and a combination of injuries and coaching changes has seen him fail to live up to his promise.
But there have been signs of improvement, and Quinzi won the all-Italian qualifying tournament to receive the wild card for the Next Gen.
Ranked 306th, with a career-high of 226th, Quinzi may be levels behind the other finalists but he will be hoping that competing once again with the players he was beaten four years ago, may give him the push to rise up the rankings.
