New York: Italian seventh seed Roberta Vinci was first through to the U.S. Open quarterfinals, taming Ukraine's Lesia Tsurenko 7-6 (5), 6-2 on Sunday.
At No. 99 the lowest ranked player to make it through to the last 16, Tsurenko represented a tricky test for last year's U.S. Open runner-up having knocked off 12th seed Dominika Cibulkova and 21st seed Irina-Camelia Begu to get to the fourth round.
The 27-year-old Ukrainian looked prepared to add another seeded scalp to her Flushing Meadows collection as she forced the first set to a tie-break before surrendering 7-5.
After a draining 67-minute opening set, Tsurenko had little left in the tank for the second and Vinci stamped her authority on the match quickly by going up a break and cruising to an easy win to clinch a spot in the last eight for the third time in four years.
Next up for Vinci is the winner between second-seeded Australian Open champion Angelique Kerber and 14th-seeded twice Wimbledon champion Petra Kvitova.
Elsewhere, Anastasija Sevastova, who quit tennis because of injury in 2013, became the first Latvian woman to reach the quarterfinals since 1994 when she beat Britain's 13th seed Johanna Konta 6-4, 7-5.
The unseeded 26-year-old, who defeated third seed Garbine Muguruza in round two, held off a late fightback from Konta to reach the last eight of a Grand Slam for the first time.
Sevastova was out of the game for 20 months until the start of last year, having announced her retirement in May 2013 after a series of injuries.
"It was hard moments for me in 2013," the 48th-ranked Sevastova said. "I was injured and not having fun and I was kind of depressed, but now I'm back."
In a topsy-turvy match, containing 12 breaks of serve, Sevastova had match point at 5-3 and another at 5-4 only for Konta to break back for 5-5.
But the Latvian regained her composure in time to hold serve and then break Konta, who was appearing in the last 16 for the second consecutive year, to clinch victory.
Konta was bidding to become the first British woman to reach the quarter-finals in New York since Jo Durie in 1983.
Earlier, Frenchman Gael Monfils, the 10th seed, defeated Marcos Baghdatis 6-3, 6-2, 6-3 to enter the quarterfinals, where he will face either compatriot Lucas Pouille or Spaniard Rafael Nadal.
In the mixed doubles, India’s Sania Mirza’s campaign came to an end as she and her Croatian partner Ivan Dodig lost their second round match to unheralded Barbora Krejcikova of Czech Republic and Marin Draganja of Croatia in straight sets 3-6, 4-6.
The match lasted for only 65 minutes as the Indo-Croat pair were outplayed in both the sets.
Mirza-Dodig were broken twice in the first four games as it became impossible to make a comeback losing the first set at 3-6.
In the second set, the Czech-Croat pair broke thrice despite being themselves broken twice to wrap the set at 6-4.
It was the 71 percent overall points that they won frst serve which made the overall difference.