Italy's Jannik Sinner returns the ball to Spain's Rafael Nadal during their men's singles quarter-final tennis match on Day 10 of The Roland Garros 2020 French Open tennis tournament in Paris on Oct 6, 2020. (MARTIN BUREAU / AFP)

Novak Djokovic feels Italian teenager Jannik Sinner leads the pack of ‘Next Gen’ players with the potential of becoming a future world number one, the Serbian said after all but securing his year-end top ranking with a win in Vienna on Wednesday.

The 19-year-old Jannik Sinner won the Next Gen ATP Finals in 2019 and is currently at a career-high ranking of 43, having reached his maiden Grand Slam quarter final at this month’s French Open

Djokovic saved four set points in the opener against Croatia’s Borna Coric to win 7-6(11) 6-3 to reach the third round of the Erste Bank Open in the Austrian capital.

The win meant that the 17-times Grand Slam winner could only be stopped from tying Pete Sampras’ record of finishing as year end No 1 for the sixth time if Rafael Nadal accepts a wild card in competing in Sofia next month.

The 19-year-old Sinner won the Next Gen ATP Finals in 2019 and is currently at a career-high ranking of 43, having reached his maiden Grand Slam quarter final at this month’s French Open.

“I definitely see a lot of quality in the young players,” said Djokovic. “(Sinner) definitely possesses a game that is powerful and is with a lot of quality, and you can say he has the potential to be a top player of the world.

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“Sinner is definitely, I would say, the leader of the guys younger than (Alexander) Zverev and (Stefanos) Tsitsipas, who I think by many experts’ opinions the next ‘top’ top player.”

German Zverev, aged 23, reached the US Open final in New York and is a year older than Greek Tsitsipas and they have won the previous two editions of the season-ending ATP Finals, the biggest event in men’s tennis outside the Slams.

Djokovic felt the duo are already established players and would need to sustain their performances over a period to wrest the top ranking.

“Many things have to come together in a career and life of a tennis player in order for him to be able to find his best and maximise his potential and to thrive every single year,” Djokovic said.

“And to endure, because I think you have a much better chance to have a great Grand Slam or a great season. But can you endure for three, four, five, 10 years? Fifteen years?”