Former French Open champion and world No.10 Barbora Krejcikova and world No.11 Beatriz Haddad Maia have crashed out in the first round of the Adelaide International.
Qualifier Anna Kalinskaya caused a sensational upset when she beat Krejcikova 7-5 3-6 7-5.
Krejcikova was left to rue 52 unforced errors to Kalinskaya's 28, despite hitting 46 winners to the Russian's 20.
World No.75 Kalinskaya had three match points on Krejcikova's serve when leading 6-5 in the deciding set and converted the third for the confidence-boosting win.
The 25-year-old is finding her feet again after a difficult run with injuries last year.
"It was a great match," Kalinskaya said.
"She's a very good fighter, she plays incredible tennis. She nows how to keep every shot, she made the match very complicated
"I'm happy that I won and I'm happy that I'm getting back in shape and playing better tennis every day.
"It feels good to play as many matches as I can after having a break, so it gives me more rhythm and confidence to go and play."
Earlier on Monday, Haddad Maia suffered a straight-sets loss to Anastasia Pavlyuchenkova in a blow to her Australian Open preparation.
Former French Open finalist Pavlyuchenkova had breezed through qualifying and made light work of the Brazilian, winning 6-3 6-4.
Cristina Bucsa teed up a round-of-16 clash against world No.3 and top seed Elena Rybakina with a comfortable 6-3 6-3 win over Jasmine Paolini.
Rybakina heads to Adelaide high on confidence after claiming the Brisbane International.
Ana Bogdan, who entered the tournament as a lucky loser, knocked out England's Katie Boulter with a 6-3 6-4 win.
World No.57 Boulter saved two match points on Bogdan's serve before the Romanian converted the third.
Earlier, Ukrainian Marta Kostyuk beat countrywoman Anhelina Kalinina 7-6 (7-3) 6-1.
Later on Monday, Paula Badosa was due to face American Bernarda Pera, with the winner to play second seed and world No.5 Jessica Pegula in the round of 16.
