Stefanos Tsitsipas took down Bulgarian No.18 seed Grigor Dimitrov 6-3, 7-6(9), 6-2 to become the first Greek, man or woman, in history to reach the Roland-Garros quarter-finals.
The 22-year-old Tsitsipas converted 3/12 break points and won 71 per cent of the points on both his first and second serve en route to a two-hour 26-minute victory.
The No.5 seed next has a rematch with Russian No.13 seed Andrey Rublev, who defeated Tsitsipas in the Hamburg final eight days ago.
Rublev battled for nearly four hours before leaping into the Roland-Garros quarter-finals for the first time in his career.
The former junior champion dug deep to extinguish the challenge of Hungarian Marton Fucsovics 6-7(4), 7-5, 6-4, 7-6(3).
Rublev is now on a nine-match winning streak and he's through to a second consecutive Grand Slam quarter-final, having reached the same stage at the US Open last month.
Petra Kvitova has returned to the Roland-Garros quarter-finals for the first time since 2012, thanks to a 6-2, 6-4 dismissal of China's Zhang Shuai in the opening match on Court Philippe-Chatrier on Monday.
The Czech No.7 seed next faces Germany's Laura Siegemund, who ousted Spaniard Paula Badosa 7-5, 6-2. Kvitova was broken while serving for the match at 6-2, 5-2 but did not waste her opportunity the second time around to book a spot in the last eight.
She improves to 4-2 in career meetings with the 39th-ranked Zhang and is now guaranteed a return to the top 10 in the world rankings.
Kvitova has now reached 13 Grand Slam quarter-finals.
Meanwhile, Polish teenager Iga Swiatek punched her ticket to the doubles quarter-finals alongside her partner Nicole Melichar with a 6-3, 6-4 success over No.6 seeds Demi Schuurs and Kveta Peschke.
Swiatek stunned top seed Simona Halep on Sunday to reach the quarter-finals in singles.
Top seed and 2016 champion Novak Djokovic faced his toughest test of the tournament so far but still came through in straight sets, 6-4, 6-3, 6-3 over No.15 seed Karen Khachanov to reach the last eight in Paris for an 11th consecutive year.