The 2019 Italian Open champion Pliskova has lost all hope to return to world No. 1, currently occupied by Japanese Naomi Osaka, after her 6-3, 6-3 defeat in almost an hour and a half at the hands of Martic.
Martic had not lost more than six games in her previous two matches combined, showing a great physical state by winning in straight sets, reports Efe news.
The 29-year-old prevailed over Ons Jabeur 6-1, 6-2 in the first round, and defeated Kristina Mladenovic 6-2, 6-1 in the second one.
The 2019 winner of the Istanbul Cup assumed her 14th victory on clay this season, recording a number more than any other tennis player; ahead of Kiki Bertens of the Netherlands and Maria Sakkari of Greece.
In the upcoming round, Martic is scheduled to take on either Kaia Kanepi of Estonia or Veronika Kudermetova of Russia.
Osaka, who is looking for her third consecutive Grand Slam title in Paris after being the 2019 US Open and Australian Open champion, has seen all the rivals who could dethrone her falling one by one including injured Kiki Bertens and Germany's Angelique Kerber.
Former world No. 1 Kerber fell 6-4, 6-2 to world No. 81 Anastasia Potapova of Russia in the tournament's first round.
In other Roland Garros action, Spaniard Carla Suarez Navarro, world No. 29, lost her campaign for the title after Czech Marketa Vondrousova defeated her 6-4, 6-4.
Vondrousova is set to square off against the winner between world No. 12 Anastasija Sevastova of Latvia or No.20 seed Elise Mertens of Belgium.
( With inputs from IANS )