Number seven seed Elena Dementieva crashed out on the opening day of the Australian Open as 18-year-old Jelena Jankovic caused the first shock in Melbourne.
The Russian was swept aside 6-1 6-4 by a player ranked number 79 in the world.
Jankovic, from Serbia & Montenegro, made a blistering start by rattling off the opening four games of the match.
Dementieva did manage a service break but Jankovic broke straight back and served out the set.
The roles were reversed in the second set as the favourite surged into a 3-0 lead.
But Jankovic reeled off the next four games to lead 4-3, only for Dementieva to break back and level at 4-4.
She self-destructed in the next game however, serving an eighth double fault at break-point down.
Jankovic took full advantage, holding her nerve and her serve to complete a major upset.
"I usually have problems at the beginning of the year," said Dementieva, who blamed her defeat on insufficient acclimatisation after spending Christmas in freezing Moscow.
"I may have to look at my schedule for next year because losing in the first round two years in a row is not good.
"I came to Australia late because I decided to be home in Moscow
for Christmas. My life is more important to me than tennis."
While Dementieva left Melbourne Park considering whether to skip the event next year, Jankovic was celebrating the best result of her short career.
"It's my first win over a top 10 player," the 18-year-old said. "I am just so happy."
Dementieva's early demise capped a miserable opening day for Russia after Nadia Petrova became the first women's seed to tumble.
Petrova made far too many errors
The number 10 seed lost 6-3 6-3 to Hungary's Aniko Kapros, ranked 80th in the world.
Petrova beat two former world number ones in Monica Seles and Jennifer Capriati on her way to the semi-finals of last year's French Open.
But she did not find any sort of form against 20-year-old Kapros, hitting eight double faults and 35 unforced errors.
Spaniard Magui Serna became the third top 16 seed to go out, despite winning the opening set.
The number 16 seed went down 6-7 7-5 6-4 to Mara Santangelo of Italy.
Slovakia's Tina Pisnik went out in straight sets, the number 26 seed falling 7-5 6-0 to Yulian Fedak of the Ukraine.
Tamarine Tanasugarn was another seed to fall as her proud Australian Open record was ended by American Laura Granville.
The 31st seed from Thailand has reached the third round in Melbourne for the past four years but slumped to a 6-1 6-3 defeat.