By Greg Stutchbury
MELBOURNE (Reuters) - Serena and Venus Williams will be looking to turn back the clock almost six years when they play their quarter-finals at the Australian Open on Wednesday.
The American sisters face the possibility of meeting each other in a grand slam for the first time since the 2009 Wimbledon final if they can first overcome tricky opponents on Rod Laver Arena, with Venus having the toughest challenge.
The 34-year-old will have to deal with teenage compatriot Madison Keys, who is widely considered one of the cleanest strikers of a tennis ball in both the men's and women's game.
Keys blasted the hard-hitting two-times Wimbledon champion Petra Kvitova off the court in the third round, with the Czech stating she had been under immense pressure from the Lindsay Davenport-coached 19-year-old.
"Yeah, definitely some similarities," Venus said when asked about the influence Davenport may be having on Keys. "Madison hits a clean ball, goes for it.
"Lindsay used to hit a clean ball. She was so fun to watch play. I loved watching her play. Of course, didn't love watching her hit those clean balls against you.
"So it looks like it's a good match."
Serena, who had a shaky start to her fourth round match with Garbine Muguruza will need to be at her best from the start against last year's beaten finalist Dominika Cibulkova, who beat two-times champion Victoria Azarenka.
Men's top seed Novak Djokovic, will also be on court in the last match of the day on Rod Laver Arena against Canada's Milos Raonic.
Djokovic, who is yet to drop a set during the tournament, met Raonic three times on tour last year and during the Davis Cup with the Serb winning each match.
Raonic, however, has improved his fitness and Djokovic said the Canadian's big serve would be a concern.
Men's champion Stan Wawrinka will also face a stiff challenge against Japan's Kei Nishikori in the other match.
(Editing by Sudipto Ganguly)