The world number two from Serbia, looking to triumph at Roland Garros for the first time, needed three sets - including two tiebreaks - to down the Canadian in the semi-finals of the Rome Masters last month.
Unheralded Muguruza has been in great claycourt form, notably defeating defending champion Serena Williams in the second round, and she will not be afraid of last year's runner-up Sharapova.
Another Canadian, Eugenie Bouchard, faces Spanish 14th seed Carla Suarez Navarro on Court Suzanne Lenglen as the 18th seed looks to match her Australian Open performance after reaching the last four in Melbourne this year.
They will be followed by Czech sixth seed Tomas Berdych and the man who downed Roger Federer in the previous round, Latvian 18th seed Ernests Gulbis.
- Sports & Recreation
- Maria Sharapova
- Court Philippe Chatrier
- Garbine Muguruza
- Serena Williams
- Carla Suarez Navarro