Life-long friends Roberta Vinci and Flavia Pennetta as well as Daniela Hantuchova reached the US Open quarter-finals to ensure five women over the age of 30 will be in the last eight.
Vinci, the 10th seed, beat compatriot and qualifier Camila Giorgi 6-4, 6-2 to reach the quarters for a second successive year yesterday.
Pennetta, now at 83 in the world, made the last eight for a fourth time with a 6-2, 7-6 (7/3) win over Romanian 21st seed Simona Halep and will tackle childhood friend Vinci with a place in a major semi-final for the first time at stake.
Slovakia's Hantuchova, who last made the quarter-finals as a teenager in 2002, saw off American wildcard Alison Riske 6-3, 5-7, 6-2 on the back of 15 aces and 46 winners.
"Roberta and I shared a room for four years. She's like a sister," said former world number 10 Pennetta, who splits a 4-4 career record with Vinci.
"I think it's going to be a really tough match for both of us. We know each other really well. I have known her for 20 years or more, we lived just 35, 45 kilometers away from each other.
"So is going to be really nice for us because one of us is going to have the chance to be in the semi-finals."
Monday's events were hard luck on Halep, who came into the tournament having won four titles on the tour this year. She was hoping to be the first Romanian in the quarter-finals since Irina Spirlea in 1997.
Halep was serving at 5-4 in the second set with a set point when torrential rain caused a suspension of play for more than four hours.
When they returned to the Louis Armstrong Stadium court, Halep's composure was shattered and Pennetta hit back before racing through the tie-breaker for victory.
Vinci recovered from 1-4 down in the first set to race away with 11 of the next 13 games to beat world number 136 Giorgi, who had stunned former number one Caroline Wozniacki in the third round.
