Just as the Australian Open women's singles event had looked like settling down, out goes the reigning Wimbledon champion and number four seed, Petra Kvitova. The 24-year-old left-hander went out in straight sets to the American teenager Madison Keys, who was no doubt inspired by her three-time Grand Slam coach Lindsay Davenport, as she watched on.

The 19-year-old ground out a 6-4 7-5 victory to end the Czech woman's title hopes for another year, in a tournament she has yet to get past the semi-final stages in. By contrast, the world number 35 can now look forward to her first fourth-round tie in Melbourne as she looks to keep her upward curve going, with an all-American match in the last-16 against Madison Brengle.

Already one set to the good, Keys maintained pace with her more noted adversary in the second set up to five games all, decisively breaking her serve and then holding on for the win.

It is becoming a decent tournament for the Americans in the women's competition, as joining Keys and Brengle in the later stages, will be Serena and Venus Williams. Both of the Williams' sisters had their struggles in their third round ties, before battling through to win in three sets. Serena came from a set down to defeat Elina Svitolina of Ukraine 4-6 6-2 6-0, while her older sister, Venus had just too much for the Italian Camila Giorgi. Venus too had to endure a first set loss before clinching the match 4-6 7-6 6-1 as she bids to reach only her second final Down Under (she lost the last one twelve years ago to her sister).

Venus continues to live with and battle against an incurable auto-immune disease these days, but her fighting spirits remain intact.

In the men's singles event, there were few surprises as both the world number one, Novak Djokovic and reigning Australian Open champion Stan Wawrinka were victorious in straight sets to reach the last-16.

Djokovic had a close battle in the first set against Fernando Verdasco before taking the tie-break 10-8, but from thereon in he settled into his normal rhythm to take the next two sets without too many concerns. Wawrinka had too much firepower for Jarkko Nieminen, as he won 6-4 6-2 6-4 to retain Switzerland's interest in the men's competition, after Roger Federer's disappointment yesterday.