Fifth seed Ana Ivanovic stunned by Lucie Hradecka

Former French Open champion Ivanovic joined double grand slam winner Sveltana Kuznetsova (27th), Swiss teen Belinda Bencic (32nd) and Sabine Lisicki (28th) as seeded casualties in early first round action.

Ivanovic, a former Australian Open finalist, had roared through the first set in 21 minutes on Rod Laver Arena and looked set to follow third seed Simona Halep into the second round after the Romanian's 6-3 6-2 win over Italy's Karen Knapp in the first game on the showcourt.

[DAY ONE ROUND-UP: Ivanovic, Kuznetsova and Lisicki all go out as seeds tumble]

However, Hradecka, who played only three WTA level events in 2014, raced through the next two sets in just over an hour to send the Serb packing and set up a second-round encounter with Slovenia's Polona Hercog.

"I played okay in the beginning. Just I felt second and third set I really dropped my level," said Ivanovic, whose only other first round exit at Melbourne Park was to Ekaterina Makarova in 2011.

"It was really tough for me to find rhythm a little bit. It's really disappointing. It's probably the worst thing (that) could happen.

"But still, the year is young and I really have to now sit and work on few things and just maybe try to have a different approach to this kind of event and try to see what was lacking."

Czech Hradecka, who plays with an unorthodox double handed grip from both sides of the court, is ranked 142nd in the world and has had most of her success as a doubles player with compatriot Andrea Hlavackova.

Ivanovic's exit was the biggest upset in the early stages of the first round, though three other seeded women were also knocked out.

Bencic was hammered 6-2 6-1 by Julia Goerges in just over an hour, while Kuznetsova, the 2004 U.S. Open and 2009 French Open champion, lost 6-4 6-2 to France's Caroline Garcia, and German Lisicki was beaten 4-6 6-4 6-2 by Kristina Mladenovic, also of France.

Kiki Bertens (Netherlands) beat Daria Gavrilova (Australia) 7-6(8) 5-7 6-2

7-Eugenie Bouchard (Canada) beat Anna-Lena Friedsam (Germany) 6-2 6-4

Carina Witthoeft (Germany) beat 17-Carla Suarez Navarro (Spain) 6-3 6-1

Yaroslava Shvedova (Kazakhstan) beat 16-Lucie Safarova (Czech Republic) 6-4 2-6 8-6

Alexandra Panova (Russia) beat Sorana Cirstea (Romania) 7-5 6-0

Silvia Soler Espinosa (Spain) beat Annika Beck (Germany) 7-5 6-4

Roberta Vinci (Italy) beat Bojana Jovanovski (Serbia) 7-5 6-1

Christina Mchale (U.S.) beat Stephanie Foretz (France) 6-4 1-6 12-10

10-Ekaterina Makarova (Russia) beat An-Sophie Mestach (Belgium) 6-2 6-2

31-Zarina Diyas (Kazakhstan) beat Urszula Radwanska (Poland) 3-6 6-4 6-2

14-Sara Errani (Italy) beat Grace Min (U.S.) 6-1 6-0

Irina Begu (Romania) beat 9-Angelique Kerber (Germany) 6-4 0-6 6-1

Monica Puig (Puerto Rico) beat Arina Rodionova (Australia) 6-0 6-3

Bethanie Mattek-Sands (U.S.) beat Duan Yingying (China) 6-4 3-6 6-3

Yanina Wickmayer (Belgium) beat 23-Anastasia Pavlyuchenkova (Russia) 4-6 6-3 6-3

Katerina Siniakova (Czech Republic) beat Elena Vesnina (Russia) 6-2 7-5

Oceane Dodin (France) beat Alison Riske (U.S.) 7-6(5) 3-6 6-3

Stefanie Voegele (Switzerland) beat Pauline Parmentier (France) 6-1 3-6 6-2

Polona Hercog (Slovenia) beat Wang Qiang (China) 3-6 6-3 6-2

22-Karolina Pliskova (Czech Republic) beat Evgeniya Rodina (Russia) 7-5 6-1

Anna Karolina Schmiedlova (Slovakia) beat Chanelle Scheepers (South Africa) 6-4 4-6 6-2

Kristina Mladenovic (France) beat 28-Sabine Lisicki (Germany) 4-6 6-4 6-2

Lucie Hradecka (Czech Republic) beat 5-Ana Ivanovic (Serbia) 1-6 6-3 6-2

Caroline Garcia (France) beat 27-Svetlana Kuznetsova (Russia) 6-4 6-2

21-Peng Shuai (China) beat Tatjana Maria (Germany) 6-4 7-5

Klara Koukalova (Czech Republic) beat Storm Sanders (Australia) 7-5 6-4

Jarmila Gajdosova (Australia) beat Alexandra Dulgheru (Romania) 6-3 6-4

3-Simona Halep (Romania) beat Karin Knapp (Italy) 6-3 6-2

Lara Arruabarrena Vecino (Spain) beat Renata Voracova (Czech Republic) 6-1 6-2

Magdalena Rybarikova (Slovakia) beat Ana Konjuh (Croatia) 6-4 6-4

Julia Goerges (Germany) beat 32-Belinda Bencic (Switzerland) 6-2 6-1