The possibility of an all-Williams semi-final at the Australian Open looked likely after both sisters won their fourth-round matches at the Rod Laver Arena today.
Defending champion Serena ended local hopeful Sam Stosur's campaign 6-4 6-2 after sixth seed Venus recovered from a sluggish start to overcome Francesca Schiavone 3-6 6-2 6-1.
The American sisters are now just one win apiece from meeting each other in the last four and the chances of that happening were increased when fourth seed Caroline Wozniacki was beaten by China's Li Na 6-4 6-3 today.
That left the Williams sisters as the highest seeded players left in the draw. Should they meet it would be their first meeting at Melbourne Park since Serena won the 2003 final.
Serena stunned the home fans inside the Rod Laver Arena with a powerful serving display to completely outgun 13th seed Stosur.
The Australian had won her previous meeting with Serena at Stanford last year, but could win just two points on her rival's serve in the first set.
The American took it 6-4 and ran away with the match in the second set to win in just over an hour.
“I can't believe it. Sam beat me last time convincingly,” Serena said.
“But I think my serve was pretty good today.”
Serena will meet the winner of tonight's match between seventh-seeded Belorussian Victoria Azarenka and Vera Zvonareva, the ninth seed, in the last eight.
Venus was optimistic she could claim her first Australian Open title after her comeback win over Schiavone.
After losing the first set the 29-year-old was down a break in the second, but turned her form around emphatically to reel off 12 of the next 14 games and seal her progress.
“She played really well in the first set. I have to give her credit, but I was able just to get some footing back in and start to execute the way I wanted to,” Venus said.
Venus faces a tricky match with 16th seed Li, who joined Zheng Jie in the quarters to ensure there would be two Chinese players in the last eight for the first time in a grand slam.
Meanwhile Andy Murray showed he has the brains as well as the brawn to win a grand slam after producing a near-flawless straight-sets victory over John Isner to reach the quarter-finals for the first time.
The fifth seed delivered on a perfectly-executed gameplan to nullify the imposing threat of the 6ft 9in American's serve and claim 7-6 (7/4) 6-3 6-2 win.
It was an unyielding display of all-round tennis from Murray as he made just eight unforced errors in a shade over two hours on the Rod Laver Arena court.
Murray will next face a top-of-the-bill clash with defending champion Rafael Nadalimprove to last five sets.
Third seed Novak Djokovic eased to another routine win to also reach the quarter-finals.
The 2008 winner needed less than two hours to claim a 6-1 6-2 7-5 win over the world number 86 Lukasz Kubot.