Denmark's Caroline Wozniacki was named top seed of a grand slam tournament for the first time on Tuesday for the US Open starting next Monday.
Wozniacki earned the seeding after a foot injury forced American Serena Williams to pull out of the Flushing Meadows tournament.
The 20-year-old Dane, the world number two behind Williams, has won three titles including a victory earlier this week at the Montreal Cup.
Defending US Open champion Kim Clijsters was named second seed, followed by two-times US champion Venus Williams, Serbia's Jelena Jankovic and Australian Samantha Stosur.
In addition to Clijsters and Venus Williams, former US Open champions seeded at the August 30-September 12 tournament are number 11 Svetlana Kuznetsova and 14 Maria Sharapova.
Francesca Schiavone, the 2010 French Open champion, is seeded sixth.
Serena Williams, who won the Australian Open and Wimbledon this year, pulled out of the US Open last week so she could recover from surgery on her foot after she cut it on broken glass at a restaurant in July.
