MELBOURNE – World number five Venus Williams and US Open champion Sloane Stephens were high-profile casualties on day one of the Australian Open Monday, but Roland Garros winner Jelena Ostapenko survived.
Williams, who lost in the final to sister Serena last year, was stunned by Swiss star Belinda Bencic, fresh from winning the Hopman Cup with Roger Federer.
The seven-time Grand Slam winner, in her 77th major, struggled against a player who had never before beaten her to go down 6-3, 7-5 and deprive the tournament of one of its biggest names.
It is the first time since 1997 that there will be neither of the Williams sisters in the second round, with Serena not playing after giving birth to her first child.
“I would like to have played someone easier,” said Bencic. “When I was a little girl watching on TV I would never imagine I would play them (the Williams).”
Also out of the opening Grand Slam of the year is American big-hitter CoCo Vandeweghe, a semi-finalist last year at Melbourne Park and Flushing Meadow.
She slumped out to Hungary's Timea Babos 7-6 (7/4), 6-2.
Stephens' poor run since winning at Flushing Meadows in September continued, with the 13th seed crashing out to Chinese number two Zhang Shuai, who made the last eight two years ago.
The frustrated American put in an error-strewn performance on an overcast and windy Melbourne day and has now not won in seven matches.
“I'm not going to get too down,” said Stephens after her 2-6, 7-6 (7/2), 6-2 defeat.
“I'm just going to stay positive and keep working to get back in the best shape and best place possible to do well for my next tournaments.”
There was better luck for Ostapenko, who saw off Francesca Schiavone 6-1, 6-4.
The seventh seed raced through the first set on Rod Laver Arena against the veteran Italian who was bizarrely wearing a back brace on the outside of her shirt.
She was 4-1 down in the second before knuckling down to race home and a second round clash with China's Duan Yingying.
“I knew before the match that it's not going to be easy. She's very experienced player and she's very long time on tour,” said the Latvian. “I knew I had to play really aggressive and stay very consistent.”
Also into the next round with a straight sets win was German 12th seed Julia Goerges, who won the lead-up Auckland Classic and is now on a 15-match unbeaten streak having ended 2017 with victories at Moscow and Zhuhai.
World number two Caroline Wozniacki, who lost to Goerges in that New Zealand decider, plays later Monday, along with men's top seed Rafael Nadal.
Sixteen-time Grand Slam champion Nadal insists he is feeling fine despite struggling with a knee injury and ready to go deep at an event that he has only won once -- in 2009 -- among his string of major triumphs.
This is despite a chequered lead-up that prevented him playing a warm-up tournament for the first time ever ahead of the opening Grand Slam of the year.
“It's a new situation for me. But I feel good,” said the 31-year-old, who first played at Melbourne Park in 2004.
Nadal, who faces the Dominican Republic's Victor Estrella Burgos in a night match on Rod Laver Arena, lost an epic Australian Open final last year to Roger Federer, who gets his campaign under way on Tuesday.
Fellow multiple Grand Slam winner Novak Djokovic, seeded 14, also starts on Tuesday, along with former world number one Maria Sharapova and top seed Simona Halep.
Among men safely through to the next round are 31st seed Pablo Cuevas and Ukrainian Alexandr Dolgopolov.