Venus Williams and Sloane Stephens crashed out as the American women suffered in the first round of the Australian Open.
The competition will take on a rather unfamiliar appearance from hereon in, with neither Venus nor Serena through to the second round after the former – the fifth seed – was beaten by Belinda Bencic on Monday.
Stephens' poor run of form continued as she too lost, and CoCo Vandeweghe was also among the series of defeated US hopefuls on the first day.
Second seed Caroline Wozniacki did manage to book a place in the next round as she edged out Mihaela Buzarnescu on Margaret Court Arena.
The same court had earlier seen more Melbourne misery for Sam Stosur as she lost once again in front of a home crowd.
However, in Daria Gavrilova and Olivia Rogowska, there were two Australians who made it safely through, while 18th seed Ashleigh Barty will be in action on Tuesday.
WILLIAMS BOWS OUT
Bencic's winning run alongside Roger Federer at the Hopman Cup appeared to inspire her against Williams, the Swiss sending the fifth seed tumbling out in the first big shock of the tournament.
Williams was runner-up 12 months ago against her sister Serena, but there will be no such run in 2018 as Bencic secured a 6-3 7-5 victory.
Venus' exit means neither Williams sister will be in the second round at Melbourne Park for the first time since 1997; the last time that happened Martina Hingis had not won a singles grand slam, golfer Tiger Woods was yet to win a major and Rafael Nadal was only 10!
STEPHENS' RUT SHOWS NO SIGN OF ENDING
Of the nine Americans dumped out of the women's draw, arguably the least surprising was the defeat of US Open champion Stephens, who has still not won since her victory at Flushing Meadows.
Zhang Shuai was her latest conqueror with a 2-6 7-6 (7-2) 6-2 victory, but Stephens was not too downhearted and is confident her form will return.
"It's not tough times, eventually I'll start [to win]," said the 24-year-old. "I'm going to beat someone eventually.
"I will have the best Instagram picture when I finally snap this losing streak."
WOZNIACKI MAKES LIGHT OF TRICKY OPPONENT
Wozniacki may be among the favourites to triumph, but she faced a challenging first-round opponent on Monday in the shape of in-form Romanian Buzarnescu.
A finalist in Hobart last week, Buzarnescu has surged up to 44th in the world rankings and produced flashes of brilliance on Margaret Court Arena.
However, the underdog's unforced error count was far too high, enabling Wozniacki to prevail 6-2 6-3 and earn a place in the second round with a degree of comfort.
NO HOME COMFORTS FOR STOSUR
Another year and more Melbourne struggles for home favourite Stosur, the 2010 French Open finalist falling at the first hurdle for the second year in a row.
In her 15 appearances at her home grand slam, Stosur has only been as far as the fourth round – in 2006 and 2010 – and that record showed no sign of improving as she was beaten by Olympic champion Monica Puig.
"I just struggle on these hard courts a bit," she said.
"I'm not going to say it's one particular thing, but if I could play on an American hard court with different balls, then I'd probably be a lot happier.
"[But] I don't really think about it. I think everyone else makes a bigger deal about it than what I do personally. I'll come back next year and do it all over again."
Compatriot Gavrilova fared much better, though, as she beat Irina Falconi 6-1 6-1.
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