Petra Kvitova and Sara Errani became the latest seeds to crash out of the Brisbane International tennis tournament Tuesday in a sign of poor form ahead of the Australian Open.
The first three days of main-draw play have seen five of the eight seeds depart, after Caroline Wozniacki and Sam Stosur crashed out on Monday and Maria Sharapova withdrew injured on Tuesday.
Fifth seed Errani fell victim to former top-10 player Daniela Hantuchova after a two-and-half hour battle, with the Slovakian prevailing 4-6, 6-1, 7-5 over her more illustrious Italian opponent.
Hantuchova now leads Errani 5-2 in their head-to-head record and meets either World No.183 Jarmila Gajdosova or lucky loser Lesia Tsurenko in the quarter-finals.
Elsewhere in second-round play, sixth seed Kvitova was beaten by Russia's Anastasia Pavlyuchenkova after an even match that ended 6-4, 7-5 to the Moscow player.
The last time the two met in Brisbane, Czech Kvitova won on her way to the 2011 title, but the rematch found her in poor form without having won more than one match at each of her last four tournaments.
Pavlyuchenkova now plays either fourth seed Angelique Kerber or qualifier Monica Puig in the quarterfinals.
The only seed to win Tuesday was Serena Williams, who downed France's Alize Cornet in straight 6-2, 6-2 sets.
Williams' quarter-final opponent will be either fellow American Sloane Stephens or Sweden's Sofia Arvidsson, both of whom defeated higher-ranked players in the first round.
There was also a minor shock as Kazakh qualifier Ksenia Pervak continued her good form to snatch a quarter-final place, making up 72 ranking spots to beat World No.31 Urszula Radwanska.
As in her first-round scalping of Caroline Wozniacki, Pervak lost the first set before winning in a tiebreak, this time beating Radwanska 3-6, 6-2, 7-6(6).
In the men's first round, eighth seed Martin Klizan of Slovakia was crushed by Uzbekistan's Denis Istomin 6-1, 6-2 in the ATP event's main upset while seventh seed Jurgen Melzer booked passage to the second round with a 2-6, 6-4, 6-4 win over U.S. qualifier Denis Kudla.