Jankovic out on day of upsets
Women's fourth seed Jelena Jankovic was the highest-profile casualty on a day of upsets at the Apia International in Sydney.
The former world number one joined Svetlana Kuznetsova and Sorana Cirstea in losing to lower-ranked opponents, while three seeds also exited the men's tournament.
World number 23 Ekaterina Makarova accounted for Jankovic 6-4 6-2 in an hour and 18 minutes, breaking serve five times to set up a clash with Spain's Carla Suarez Navarro, who beat Paula Ormachea 3-6 7-6 (7/5) 6-2.
And Varvara Lepchenko and Tsvetana Pironkova will meet in a surprise second-round clash after upsetting Kuznetsova and Cirstea respectively.
Lepchenko won 6-3 3-6 7-5 against the former French and US Open champion while Pironkova stormed to a 6-4 6-1 win over a player ranked 85 places above her at 22nd in the world.
Fifth and sixth seeds Angelique Kerber and Caroline Wozniacki progressed, though the latter had to battle to a 3-6 6-2 6-4 win over Germany's Julia Goerges.
Goerges' compatriot Kerber beat Dominika Cibulkova of Slovakia 7-6 (7/5) 7-5.
Kaia Kanepi, Lucie Safarova and United States trio Bethanie Mattek-Sands, Lauren Davis and Christina McHale were the day's other winners.
In the men's draw, sixth seed Julian Benneteau downed home wild card Matthew Ebden 6-2 6-2 but Albert Ramos, Jiri Vesely and Alex Bogomolov Jr were all eliminated.
Spaniard Ramos, seeded fifth, took the opening set against Slovenia's Blaz Kavcic but was broken twice in each of the next two to lose 4-6 6-4 6-2.
Russian eighth seed Bogomolov lost 6-3 2-6 7-6 (7/3) to American Ryan Harrison while Vesely, the seventh seed from the Czech Republic, lost in successive tie-breaks to Germany's Jan-Lennard Struff.
Sergiy Stakhovsky, best known for his upset of Roger Federer at Wimbledon last year, beat Federer's fellow Swiss Henri Laaksonen 6-1 6-1 while Lukas Rosol, the 2012 conqueror of Rafael Nadal at SW19, edged out Portugal's Joao Sousa 7-6 (7/5) 4-6 7-6 (7/1).
Denis Istomin of Uzbekistan was a 6-2 6-1 winner against Spain's Pablo Andujar.