Experience won out on a rain-affected day as Daniela Hantuchova, Flavia Pennetta and Roberta Vinci reached the quarter-finals at the US Open.

Along with Serena Williams and Li Na, who won their fourth-round matches yesterday, there are five women over 30 still left in the tournament, the most at this stage of a grand slam for 36 years.

Tenth seed Vinci was the only one to complete her victory before a four-and-a-half-hour delay as the heavens opened over Flushing Meadows.

The Italian ended the run of her countrywoman Camila Giorgi with a 6-4 6-2 victory and will play another Italian, Pennetta, in the quarter-finals.

Giorgi came through qualifying and beat sixth seed Caroline Wozniacki in the third round, but she made 35 unforced errors compared to her opponent's nine.

Vinci, 30, reached the last eight in singles at a grand slam for the first time here 12 months ago but lost to doubles partner and best friend Sara Errani.

Pennetta met in-form Simona Halep, and the timing of the rain was unfortunate for the Romanian, who had a set point to level the match when it was suspended.

When they began again four and a half hours later, she promptly lost the first three points to drop serve.

Halep broke again to lead 6-5 but Pennetta broke back to force a tie-break, which she won convincingly to clinch a 6-2 7-6 (7/3) victory.

The US Open has been the 31-year-old's best grand slam and this will be her fourth quarter-final at Flushing Meadows.

Pennetta beat Maria Sharapova here two years ago but missed last year's tournament after having wrist surgery, which kept her out for six months.

A former top-10 player, the Italian is currently ranked only 83rd, but will climb significantly now, especially if she can reach her first grand slam semi-final.

Pennetta said: "It was and still is really tough. A lot of things changed when I came back. Everything was really different, from my coach, from my doubles partner, from the feeling I had in the court, everything.

"I cried a lot. But I love this sport. I wanted to have a chance just to prove myself. Now the result, it's good."

Hantuchova, 30, defeated US wild card Alison Riske 6-3 5-7 6-2 to reach her first grand slam quarter-final since the Australian Open in 2008.

The Slovakian, ranked 48th, lost in the first round at this year's other three grand slams and had to save four match points in her third-round win over Julia Glushko.

Hantuchova said: "This tournament is only starting now for me. It just means the world to me to be again in the quarter-finals."

Meanwhile, US Open organisers opted to cancel the remainder of the day session on Arthur Ashe, meaning the standout tie of the fourth round in the bottom half of the draw between second seed Victoria Azarenka and Ana Ivanovic will be played on Tuesday.

Although one match was completed, the United States Tennis Association activated their inclement weather policy, meaning Ashe ticket-holders can exchange their tickets for a comparable session next year.

The women's quarter-finals begin on Tuesday, with Li meeting Russia's Ekaterina Makarova before Williams takes on Carla Suarez Navarro in the night session.