Muguruza, who improves her win-loss record at Roland-Garros to 26-5, next faces ninth seed Elina Svitolina in a blockbuster third-round encounter.
Svitolina earlier on Wednesday progressed without hitting a ball; her opponent Kateryna Kozlova withdrew citing a viral illness.
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Elsewhere around the grounds, 20th seed Elise Mertens stopped French teenager Diane Parry for the loss of just four games while Veronika Kudermetova beat Zarina Diyas 7-5, 6-1.
In the men's draw, top-10 seeds Rafael Nadal, Stefanos Tsitsipas and Kei Nishikori are currently in action on the tournament's three biggest courts.
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In a big upset, local wildcard Corentin Moutet stunned 19th seed Guido Pella - the player with the most match wins on clay in 2019 - in four sets.
The 20-year-old sent the crowd into a frenzy on Court 7 thanks to a 6-3, 6-1, 2-6, 7-5 triumph.