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. Photograph: (AFP)
World number one Nadal, who could meet old rival Roger Federer for the first time in New York at the semi-final stage, crushed Ukraine's Alexander Dolgopolov 6-2, 6-4, 6-1
Rafael Nadal notched up his 50th win at the US Open to reach the quarter-finals for the seventh time Monday as teen sensation Andrey Rublev and comeback queen Kaia Kanepi muscled into the spotlight.
World number one Nadal, who could meet old rival Roger 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 quarterfinal, the women's draw saw Estonia's world number 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.
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 number 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 53, 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.
Federer, bidding for a sixth US Open and 20th major, will tackle Philipp Kohlschreiber later Monday.
After stretching his runs of dominance over Mikhail Youzhny to 17-0 and Feliciano Lopez to 13-0, the 36-year-old Federer takes an 11-0 advantage into his night-time duel with German 33rd seed Kohlschreiber.
The remaining last-16 tie of the day sees 2009 champion Juan Martin del Potro, the 24th seeded Argentine, up against Austrian sixth seed Dominic Thiem.
Thiem, who was forced to quit with an injury against del Potro at the same stage in 2016, celebrated his 24th birthday on Sunday.
The 32-year-old Kanepi, a former world number 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.
It will be Kanepi's sixth quarter-final at the majors and second in New York after also reaching the last eight in 2010.
"It's very tough to believe where I am now after all that has happened. I didn't expect it," said Kanepi, who is playing in the main draw of an event for the first time this year.
In 2016, she appeared just once in Rabat as she battled the effects of Epstein-Barr virus and then painful plantar fasciitis in both feet.
Top seed Kristina 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).