Former world number one Caroline Wozniacki started the new season in shocking fashion, losing 2-6 6-3 7-6 to to Kazakhstan qualifier Ksenia Pervak in the first round of the Brisbane Open on Monday.
And top Australian Sam Stosur also crashed out, losing to 7-6 7-5 to Sweden's Sofia Arvidsson.
Stosur has traditionally struggled in her homeland, and she threw in 48 unforced errors in falling to Arvidsson.
Wozniacki started well enough, racing into a 4-1 and rattling off the first set in less than 30 minutes.
But as the match proceeded she started struggling with her serve and battled to contain the hard-hitting Kazak's groundstrokes.
The 103-ranked Pervak, who had lost in the first round of 14 tournaments last year, grew in confidence and levelled the match by taking the second set 6-3.
Pervak then opened up a 5-3 lead in the decider but lost her nerve briefly when serving for the match to allow the Dane to level matters at 6-6.
But Pervak raced to a 6-1 lead in the resulting tie-break and didn't let Wozniacki off the hook again.
Eight of the top 10 ladies on the WTA rankings take part in the Brisbane event ahead of the Australian Open, but now Wozniacki will head to Sydney hoping for some decent match practice.
"I fought until the end. Maybe didn't play my best tennis today, but it's tough to expect that from yourself in your first match back," Wozniacki commented after her defeat.
"Now I just have to play some practice matches with some of the other girls here and then go to Sydney and hopefully get a couple more there."
McIlroy rumours denied
Wozniacki was also quick to dismiss claims that she'd got engaged to the world's top golfer Rory McIlroy. The Ulsterman was in the crowd at the Pat Rafter Arena watching her play.
Rumours about the pair's engagement has been rife after Wozniacki was photographed with a new ring on her left hand, but the 22-year-old explained on Monday that the ring was a Christmas gift.
"It was a Christmas present and it fit on this finger and I put it on, and all of a sudden I hear that I'm engaged. But I'm not," she said.
"So, yeah, it's already twice we've had to shut down engagement rumors. Don't worry, we will let you know if that time happens!"
In earlier matches, the fourth-seeded Angelique Kerber recorded a 6-2, 4-6, 6-2 win over Anna Tatishvili while French Open runner-up Sara Errani beat Olga Puchkova 6-1, 6-3.
Alice Cornet will face Serena Williams in the second round after beating Australian qualifier Bojana Bobusic 2-6, 6-3, 6-1, and Sabine Lisicki opened with a 6-2, 6-4 win over Lucie Safarova. She will play current world number one Victoria Azarenka in the next round.