Sunday at the US Open
The biggest clash of the US Open so far takes place on Sunday as Maria Sharapova faces Caroline Wozniacki, while Roger Federer is also back in action at Flushing Meadows.
As seeds have tumbled in the women's draw, another one will bite the dust on Sunday with fifth seed Sharapova taking on 10th seed Wozniacki on Arthur Ashe.
It will mean just four of the top ten seeds will remain after the match, giving the winner a big chance of making a big push for the title.
Neither Sharapova or Wozniacki were tested in their third round matches, but it will be a big step up for both 2006 winner Sharapova and 2009 runner-up Wozniacki.
The Russian holds the upper hand in the head-to-head record with five wins and just two defeats, but both of Wozniacki's wins have come on hard courts.
Five-time champion Federer brings the daytime session to a close as he plays unseeded Spaniard Marcel Granollers looking for his 14th straight place in the US open fourth round.
Federer has won both of their previous meetings and has an impressive 50-4 record in third round matches at Grand Slams to protect.
Both men came through against big servers in the previous round, with Federer beating Sam Groth and Granollers surviving 31 aces to win a five-setter against Ivo Karlovic.
The play kicks off on Ashe with 32-year-old Mirjana Lucic-Baroni continuing her dream run against Italian 13th seed Sara Errani.
Lucic-Baroni won the junior US Open title back in 1996 and is in the fourth round of a major for the first time since 1999 after beating world No 2 Simona Halep in the last round and is one of the big stories of the tournament so far.
In contrast, the evening session kicks-off with the youngest player in the draw taking to the court as 17-year-old Belinda Bencic faces former world No 1 Jelena Jankovic.
If the Swiss starlet manages to come through the tie she'll be the youngest US Open quarter-finalists since Martina Hingis went on to win the title back in 1997 as a 16-year-old.
Two of the sport's young guns then go head-to-head in what should be an entertaining late match as Bulgaria's Grigor Dimitrov plays Belgian David Goffin.
Dimitrov is growing in stature after his run to the semi-finals at Wimbledon this year, while Goffin is trying to beat a top 10 player for the first time in his 11th attempt.
Over on Louis Armstrong, fourth seed David Ferrer goes up against Frenchman Gilles Simon, while there's an all-French battle in the final match with Gael Monfils and Richard Gasquest squaring off.