'09 US Open champ del Potro saves match points; Federer next
court for a medical timeout. He said afterward it was so he could get a massage after feeling a muscle tightening at the top of the back of his left leg.
His back had been bothering Federer before the US Open and restricted his practice time, something he blamed for problems while getting pushed to five sets in each of the first two rounds last week. But the lopsided win agai nst Kohlschreiber — who never held a break point — was Federer's second in a row in straight sets.
Federer improved to 12-0 agai nst Kohlschreiber; his record against del Potro is 165. But del Potro won their meeting in the 2009 final in New York in five sets for his only Grand Slam title, ending Federer's streak of five straight US Open championships — and he hasn't won the trophy since.
"I felt like that I left that match with a lot of regrets," Federer said.
The other matchup on that half of the men's bracket will be No. 1 Rafael Nadal against 19year-old Andrey Rublev, the youngest quarterfinalist at the US Open since Andy Roddick was 19 in 2001.
Nadal got to the round of eight in New York for the first time since his 2013 title, overwhelming 64thranked Alexandr Dolgopolov 6-2, 6-4, 61.
"Every victory, every set that you win, is more confidence," Nadal said. "That what's I am doing."
Now Nadal gets to play a fifth consecutive unseeded foe in Rublev, who took out No. 9 David Goffin 7-5, 7-6 (5), 6-3.
There are four Americans in the women's quarterfinals in New York for the first time in 15 years after No. 15 Madison Keys grabbed the last four games to top No. 4 seed Elina Svitolina of Ukraine 7-6 (2), 1-6, 6-4 in Monday's last match.
No. 20 CoCo Vandeweghe beat Lucie Safarova 6-4, 7-6 (2) earlier Monday, while Venus Williams and Sloane Stephens advanced Sunday.
Vandeweghe's quarterfinal opponent is No. 1 seed Karolina Pliskova, the 2016 runner-up, who beat 91stranked American Jennifer Brady 6-1, 6-0.
Keys now faces Estonia's Kaia Kanepi, who beat Daria Kasatkina 6-4, 6-4 to become the first qualifier in 36 years to reach the U.S. Open women's quarterfinals.
The 32-year-old Estonian is ranked 418th after missing much of the past two years with problems in the soles of both feet and a virus nown as a precursor to mononucl eosi s.
"It's pretty amazing where I am now," Kanepi said, "compared to where I was few months ago."
(AP)