The Serbian, who occasionally struggled for momentum in her service games as her ball toss caused her problems, was never able to keep pace with world No. 11 Pliskova - just a week after losing to Britain's Naomi Broady - as her difficult preparations for the Australian Open continued.
"It was a solid win for me today," Pliskova said afterwards. "She is always tough to play. I'm happy to have more matches."
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Another former world No. 1, Jelena Jankovic, at least avoided Ivanovic's fate - beating Coco Vandeweghe 6-3 6-4 to bounce back after her surprise first round exit in Brisbane a week earlier.
Sixth seed Timea Bacsinszky joined Ivanovic in making an early exit, as she was beaten 1-6 6-1 6-3 by Anna Karolina Schmiedlova despite making a blistering start.
Elsewhere in Sydney, previous champion Tsvetana Pironkova beat Lesia Tsurenko 7-6 6-2, while Svetlana Kuznetsova was even less troubled as she clinched a 6-2 6-0 win over Tammi Patterson.
In the all-French tie between Caroline Garcia and Kristina Mladenovic, it was the former who triumphed as she edged an opening set tiebreak on the way to a 7-6(4) 6-4 victory.
The tournament in Sydney has got off to a rocky start, with both Agnieszka Radwanska and Petra Kvitova withdrawing due to injury.
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