Updated

Italian veteran Roberta Vinci secured a berth in her second straight U.S. Open quarterfinal with a straight- set victory, while American Alison Riske came up a loser on a rainy Monday in New York.

The 30-year-old, 10th-seeded Vinci leveled 21-year-old qualifier Camila Giorgi 6-4, 6-2 in 67 minutes in an all-Italian fourth-round affair on the Grandstand court. Moments later it started pouring at the USTA Billie Jean King National Tennis Center, prompting a more-than-four-hour rain delay on Labor Day in the United States.

Giorgi, who stunned former world No. 1 and former U.S. Open runner-up Caroline Wozniacki in the third round on Saturday, broke serve only once on Day 8 while Vinci recorded four breaks en route to victory.

Vinci has never reached a major quarterfinal outside of New York City. She's a three-time Grand Slam doubles champ with her fellow countrywoman Sara Errani, including last year's U.S. Open and this year's Australian Open titles.

Up next for Vinci will be another compatriot in 31-year-old Flavia Pennetta.

"This is good for Italian tennis," Vinci said. "Italian tennis (is) going up."

Following that hours-long rain delay, the one-time world No. 10 Pennetta returned to the court to finish off 21st-seeded Romanian Simona Halep, 6-2, 7-6 (7-3), in 1 hour, 29 minutes. Pennetta tallied five service breaks, compared to three for Halep.

The rising Halep headed to Flushing having won four of her last seven tournaments, including one in New Haven the week before the 2013 U.S. Open.

Pennetta, who missed last year's U.S. Open because of injury, will now play in her fourth quarterfinal here in her last five trips to New York.

The 23-year-old Pittsburgh native Riske gave way to one-time world No. 5 Daniela Hantuchova, 6-3, 5-7, 6-2, in just over two hours following the long delay that sent the players off the court in the second set. The Slovakian Hantuchova had twice as many breaks (4-2) on her way to the round of eight.

The 30-year-old Hantuchova reached her first U.S. Open quarterfinal in 11 years and first Grand Slam quarter since appearing in the semifinals at the 2008 Aussie Open.

"This tournament is only starting now for me. It just means the world to me to be again in the quarterfinals," Hantuchova said.

Meanwhile, a match between second-seeded former world No. 1 Victoria Azarenka and 13th-seeded former top-ranked star Ana Ivanovic was postponed until Tuesday. The reigning Australian Open champion Azarenka was last year's U.S. Open runner-up to the mighty Serena Williams.

The women's quarterfinals are scheduled to get underway Tuesday, as the world No. 1 Williams will meet 18th-seeded Spaniard Carla Suarez Navarro and fifth-seeded Aussie Open runner-up Li Na of China will face 24th-seeded Russian Ekaterina Makarova.

The reigning champion and four-time U.S. Open titlist Williams owns 16 Grand Slam titles overall, including this year's French Open.