"Oh my God, I don't know (I won). What can I say after a battle like this. I was sick the last two days and I just tried to improve game after game," Del Potro said after his match. "I fought like this because of you guys, so thank you very much," he added, pointing to the Argentine fans in the crowd. Del Potro now faces Federer, whom he beat in the final in New York for his only grand slam title. The Swiss third seed took an easier route into the quarter-finals, firing 11 aces and 39 winners as he despatched Germany's Philipp Kohlschreiber 6-4 6-2 7-5 in one hour, 45 minutes. The only worry for Federer would be the condition of his back after he left the court midway through the match for treatment. The Swiss, who started slowly at New York due to the niggling issue, allayed fears after his match.DELPO DOES IT!
Thiem double faults on match point & the comeback is complete for @delpotrojuan! He wins 1-6, 2-6, 6-1, 7-6, 6-4.#USOpen pic.twitter.com/Gw6Kcb3GQx— US Open Tennis (@usopen) September 5, 2017
.@rogerfederer defeats Kohlschreiber 6-4, 6-2, 7-5 to set up a highly anticipated QF against Del Potro!#USOpen pic.twitter.com/0MbQnlGhsj— US Open Tennis (@usopen) September 5, 2017"I just felt something, sort of my muscle being tight at the back," said Federer. "I wanted to get it done really quickly after the set break. It was more precaution. It's all good. No problems there. I'm not worried about it." World number one Nadal made short work of Alexandr Dolgopolov 6-2 6-4 6-1 and the French Open champion now faces Russia's Andrey Rublev, after the 19-year-old knocked out ninth-seeded Belgian David Goffin 7-5 7-6(5) 6-3.
Women's top seed Karolina Pliskova of Czech Republic routed American Jennifer Brady 6-1 6-0 to set up a match with American 20th seed CoCo Vandeweghe who beat Lucie Safarova 6-4 7-6(2). American Madison Keys smashed 46 winners but also committed 52 unforced errors in her 7-6(2) 1-6 6-4 win over Ukraine's fourth seed Elina Svitolina.Q: Do you remember what it was like to be 19 and what was the best part of it? @RafaelNadal: 19? Rublev is 19?#USOpen pic.twitter.com/GDQZS3b1fs
— US Open Tennis (@usopen) September 5, 2017
No.20 @CoCoVandey continues her deepest run in ?, d. Safarova 6-4, 7-6(2) to book a QF clash vs Pliskova ? https://t.co/zTS8OLK5Ye #usopen pic.twitter.com/2lBGPD1Km8— US Open Tennis (@usopen) September 4, 2017The 15th seed now faces world number 418 Kaia Kanepi of Estonia who cruised past Russian Daria Kasatkina 6-4 6-4. Highlights from day eight of the U.S. Open tennis championships on Monday (times GMT):KEYS BATTLES TO DOWN SVITOLINA- American 15th seed Madison Keys overcame a mid-match scare to defeat Ukraine's fourth seed Elina Svitolina 7-6(2) 1-6 6-4 in two hours.
- Keys smashed 46 winners but also committed 52 unforced errors. - The American faces Estonia's world number 418 Kaia Kanepi in the quarter-finals.FEDERER CRUISES PAST KOHLSCHREIBER- Five-time champion Roger Federer booked his place in the quarter-finals with a 6-4 6-2 7-5 victory over German Philipp Kohlschreiber. - The third seed Swiss will face 2009 winner and 24th seed Juan Martin del Potro for a place in the final four.DEL POTRO CLAIMS SPECTACULAR COMEBACK WIN- Juan Martin del Potro saved two match points before completing a thrilling comeback from two sets down to beat Austria's Dominic Thiem 1-6 2-6 6-1 7-6(1) 6-4 in the fourth round.RUSSIAN TEENAGER RUBLEV STUNS GOFFIN- Russia's Andrey Rublev knocked out ninth-seeded Belgian David Goffin 7-5 7-6(5) 6-3 in the round of 16. - The 19-year-old Rublev became the youngest U.S. Open men's quarter-finalist since American Andy Roddick in 2001. - He will meet top seed Rafa Nadal for a place in the final four.NADAL EASES PAST DOLGOPOLOV- World number one Rafa Nadal reached the quarter-finals of the U.S. Open for the first time in four years with a 6-2 6-4 6-1 victory over Ukraine's Alexandr Dolgopolov..@Madison_Keys upsets Svitolina 7-6(2), 1-6, 6-4!
Secures last spot in #USOpen Quarterfinals--> https://t.co/pvDURDY7m5 pic.twitter.com/gN432SawsB— WTA (@WTA) September 5, 2017
When you make a 23,000-seat stadium feel cozy. Sweet moments between @RafaelNadal & US Open fans after his R4 win in Ashe ??? #usopen pic.twitter.com/7HVyuZ8zpV— US Open Tennis (@usopen) September 4, 2017- Two-time U.S. Open winner Nadal is on course to win his second grand slam of the year after sealing the French Open title in June.PLISKOVA CRUISES INTO QUARTER-FINALS- Top-seeded Karolina Pliskova of Czech Republic dropped a single game as she beat American Jennifer Brady 6-1 6-0 to progress to the quarter-finals.
- The world number one, who lost to German Angelique Kerber in last year's U.S. Open final, will face either American CoCo Vandeweghe or compatriot Lucie Safarova in the next round.PLAY BEGINS AT FLUSHING MEADOWS- Swiss world number three Roger Federer takes on Germany's Philipp Kohlschreiber and women's fourth-seed Elina Svitolina of Ukraine faces American Madison Keys at the main showcourt later on Monday. - Ninth seed Goffin plays Rublev, who ousted seventh seed Grigor Dimitrov in the second round, at Louis Armstrong stadium. - Sixth-seeded Austrian Dominic Thiem will face Argentina's 24th seed Juan Martin del Potro in the late match at the Grandstand Stadium.#ICYMI@Petra_Kvitova's incredible resurgence is the story of the #USOpenhttps://t.co/o97OPlRjKG pic.twitter.com/u9MZHetOnK
— The Field (@thefield_in) September 5, 2017
.@USOpen Schedule of Play | Day 9: Tuesday, 5th September 2017 https://t.co/6e3qs5uzHmpic.twitter.com/w7RAYe2bMB— Topspin Stringing (@RealTopspin) September 5, 2017