NEW YORK (AFP) - Five-time champion Roger Federer set-up a mouthwatering US Open quarter-final clash against 2009 winner Juan Martin del Potro on Monday.
Third seed Federer defeated Philipp Kohlschreiber 6-4, 6-2, 7-5 to take his record over the German to 12-0.
Del Potro, who defeated Federer in the 2009 final for his only Grand Slam title, saved two match points to knock out Austrian sixth seed Dominic Thiem 1-6, 2-6, 6-1, 7-6 (7-1), 6-4 in his fourth-round match.
Rafael Nadal notched up his 50th win at the US Open to reach the quarter-finals for the seventh time as teen sensation Andrey Rublev and comeback queen Kaia Kanepi muscled into the spotlight.
World No. 1 Nadal, who could meet old rival Federer for the first time in New York at the semi-final stage, crushed Ukraine's Alexander Dolgopolov 6-2, 6-4, 6-1.
The 31-year-old Spaniard goes on to face Russian 19-year-old Rublev, who stunned Belgian ninth seed David Goffin 7-5, 7-6 (7-5), 6-3 to become the youngest quarter-finalist since Andy Roddick in 2001.
As Rublev pondered a first Slam quarter-final, the women's draw saw Estonia's world No. 418 Kanepi book her place in the last eight of a major for the sixth time.
The 32-year-old is just the second qualifier to make the quarters in New York.
Kanepi, a former world No. 15 whose career was almost ended by illness and a crippling injury, downed Russia's Daria Kasatkina 6-4, 6-4. She will next face either Ukrainian fourth seed Elina Svitolina or Madison Keys of the United States.
Nadal, the 2010 and 2013 champion, showed no signs of the struggles that bedeviled him in the two previous rounds, when he dropped the opening set before prevailing in four. His 23 winners were just shaded by world No. 64 Dolgopolov's 25 but the Ukrainian's 39 unforced errors were more than three times those committed by Nadal.
"I played a solid match with not many mistakes," said Nadal, the reigning French Open champion. "He's a player who can play amazing shots but sometimes he can be very unpredictable so I just waited for my opportunity."
Rublev, ranked 53rd, has won 13 of his last 17 matches after breaking the top 100 for the first time in June. He marked his entry into the top 50 by winning the Umag title as a lucky loser in July and he insists all the pressure will be on Nadal who is chasing a 16th major.
"Rafa is a real champion. I will try to do my best - I have nothing to lose," said Rublev, whose push to victory on Monday was helped by Goffin suffering a left knee injury. "It was impossible to win today," said the Belgian.
Top seed Karolina Pliskova, the runner-up in 2016, needed just 46 minutes to sweep past Jennifer Brady of the United States 6-1, 6-0 and make her third Slam quarter-final of 2017. The tall Czech had needed back-to-back three-setters to get to the last 16, including having to save a match point against Zhang Shuai of China in the third round.
Pliskova will next face American 20th seed CoCo Vandeweghe, who made the last eight for the first time by beating Lucie Safarova of the Czech Republic 6-4, 7-6 (7-2).