Maria Sharapova reached the US Open quarter-finals for the first time since her 2006 championship run with a 6-1, 4-6, 6-4 victory over Russian compatriot Nadia Petrova on Sunday.
And defending champion Samantha Stosur of Australia set up a last-eight showdown with top seed Victoria Azarenka as both captured fourth-round triumphs on the Flushing Meadows hardcourts at the year's last Grand Slam.
Third seed Sharapova, who completed a career Grand Slam by capturing the French Open title last June, rallied after twice dropping four games in a row and having to sit through a 73-minute rain delay.
"I'm so happy to be in the quarters," Sharapova said. "It has been so many years and it's a great stage to be at."
Seventh seed Stosur squandered eight match points but finally subdued stubborn British teen prodigy Laura Robson 6-4, 6-4 in 98 minutes.
She will take on world No. 1 Azarenka of Belarus, who ousted Georgia's Anna Tatishvili 6-2, 6-2, to reach her first US Open quarter-final.
Sharapova will next face French 11th seed Marion Bartoli, who beat Czech fifth seed Petra Kvitova, the 2011 Wimbledon winner, 1-6, 6-2, 6-0, to book her first trip to the US Open quarter-finals at her 11th attempt.
Defending champion Novak Djokovic stormed into the last 16 on Sunday as Andy Roddick stretched his long goodbye into a prime-time showdown with fellow former champion Juan Martin Del Potro.
Djokovic coasted past French 30th seed Julien Benneteau 6-3, 6-2, 6-2 despite being forced to open up play on day seven at Arthur Ashe Stadium.
He goes on to face Swiss 18th seed Stanislas Wawrinka, a semi-finalist in 2010 who eased past 14th-seeded Ukrainian Alexandr Dolgopolov 6-4, 6-4, 6-2 for a spot in the quarter-finals.
American 20th seed Roddick delayed his retirement by advancing to the fourth round with a 7-5, 7-6 (7/1), 4-6, 6-4 victory over Italy's Fabio Fognini.
Del Potro defeated 63rd-ranked compatriot Leonardo Mayer 6-3, 7-5, 7-6 (11/9) in a three-hour 20-minute marathon which was wrapped up on his sixth match point.
While Roddick survived, another former champion, 2001 winner Lleyton Hewitt, was knocked out by low-profile Spanish fourth seed David Ferrer, a semi-finalist in 2007, who clinched a 7-6 (11/9), 4-6, 6-3, 6-0 win.
The latest example of John Isner's knack for playing marathon matches - and, lately, losing them - was a 6-4, 3-6, 4-6, 6-3, 6-4 third-round exit at the U.S. Open against Philipp Kohlschreiber that ended at 2:26 a.m. Monday, tying the tournament record for latest finish.
Isner left all four Grand Slam tournaments this year with five-set losses, and he didn't make it past the third round at any of them. "It's disappointing,: he said, staring down at the floor.
The 19th-seeded Kohlschreiber won his sixth consecutive five-setter. The official completion time of this one was the same as a second-round US Open match in 1993, when Mats Wilander beat Mikael Pernfors.
That length pales in comparison to Isner's record 11-hour, 5-minute victory that stretched over three days at Wimbledon in the first round in 2010, and his 5-hour, 41-minute loss at the French Open in the second round in May.
No Rafa in Davis Cup
Rafael Nadal has extended his long injury layoff by another two months and will miss his country's Davis Cup semi-final against the United States.