Milan – South Korean Hyeon Chung became the first player to book his ticket to the semi-finals of the Next Gen ATP Finals in Milan on Wednesday.
The 54th-ranked Chung made it two wins out of two in the round robin format being used in the inaugural edition of the under-21 version of the ATP Tour finals.
Chung beat Russia's Andrey Rublev 4-0, 4-1, 4-3 (7/1) on Wednesday in their Group A match a day after rallying from a set down to get past Canadian Denis Shapovalov.
"The score looks easy, but it was not easy on the court. Every point was a fight," said 21-year-old Chung who is guaranteed of finishing top of the group.
Pre-tournament favourite Rublev, ranked 37th and winner of his first title in Umag this year, had won his opener against Italian wildcard Gianluigi Quinzi.
Rublev can still make the semi-finals on Thursday when he plays Shapovalov.
The tournament has brought together eight emerging stars tipped as the Rafael Nadal, Andy Murray, Novak Djokovic and Roger Federers of the future.