Denmark's Caroline Wozniacki has advanced to the quarter-finals at the US Open after beating five-time grand slam champion Russian Maria Sharapova in three sets.
Sharapova, the reigning French Open champion and winner at Flushing Meadows in 2006, took a 5-2 record over the Dane into this morning's fourth-round clash, which Wozniacki won 6-4 2-6 6-2.
Three of those victories had come since Wozniacki last beat her in 2011.
Tenth-seeded Wozniacki, the 2009 US Open runner-up, will face 13th-seeded Italian Sara Errani for a place in the semi-finals.
Earlier, Errani became the first woman through to the quarter-finals this year, following a 6-3 2-6 6-0 victory over Croatian qualifier Mirjana Lucic-Baroni.
Errani, who completed a career doubles grand slam with Roberta Vinci at Wimbledon, is trying to improve on her best singles showing in a major, a runner-up finish at the 2012 French Open.
The 27-year-old Italian, ranked 14th in the world, ended an emotional run for 32-year-old Lucic-Baroni, a teen sensation in the 1990s who is now ranked No.121 in the world.
Lucic-Baroni had shocked world number 2 Simona Halep to reach the last 16.
A first set scare and a two hour rain delay couldn't put five time champion Roger Federer off his stride as he advanced to the fourth round of the US Open in New York.
The 33 year old Federer who's bidding to become the oldest grand slam champion in more than 40 years, came back from a set down to beat world number 42 Marcel Granollers of Spain 4-6 6-1 6-1 6-1 racing away with 20 of the last 24 games of the match.
Federer will play Spain's Roberto Bautista Agut for a place in the quarter-finals.
The Spanish fourth seed David Ferrer suffered his earliest US Open exit in five years beat 6-3 3-6 6-1 6-3
by the 26th seeded Frenchman Giles Simon.
Simon now plays Marin Cilic of Croatia, who beat South Africa's Kevin Anderson also in four sets.
Czech sixth seed Tomas Berdych, a semi-finalist in 2012, beat Georgian-born Russian Teymuraz Gabashvili 6-3 6-2 6-4 and next plays Dominic Thiem of Austria, the youngest player in the top 50 at just 20.
The Bulgarian seventh seed Grigor Dimitrov, who had never won a match in New York in three appearances before this year, is a potential quarter-final opponent of Federer.
The 23-year-old Dimitrov plays Belgium's David Goffin, the world No.56, for the first time.