Martina Navratilova backed Serena Williams to create history by sweeping to a calendar-year Grand Slam after she marched into the Australian Open quarter-finals. The tennis legend described Williams as the greatest player of her generation -- and said "if anyone can, Serena can" achieve the holy grail of winning all four major titles in the same year.

"We know that Serena at her best is better than anybody else out there, if for no other reason than her serve. It sets everything up."