Shnaider won six straight games in the first set and came back from a 2-0 hole in the second set to win in 75 minutes.
Denmark's Clara Tauson eliminated Fruhvirtova 6-2, 7-6 (6).
In other second-round matches, Martina Trevisan upset 15th-seeded Jasmine Paolini 7-5, 6-2 in an all-Italian matchup, and seventh-seeded Veronika Kudermetova of Russia downed Canada's Eugenie Bouchard 6-2, 6-7 (4), 6-4.
Colombia's Emiliana Arango knocked out 11th-seeded Russian Anastasia Potapova 6-4, 6-3, and Italy's Camila Giorgi defeated Egypt's Mayar Sherif, the No.
14 seed, 7-5, 6-3.
Persons:
Maria Sakkari, Russia's Diana Shnaider, Carl Recine, Diana Shnaider, Claire Liu, Shnaider, Liu's, Linda Fruhvirtova, Denmark's Clara Tauson, Magda Linette, Jodie Burrage, Minnen, Harriet Dart of, Akron Hailey, Karolina Pliskova, Baptiste, Pliskova, Martina Trevisan, Jasmine Paolini, Veronika Kudermetova, Canada's Eugenie Bouchard, Victoria, Caroline Dolehide, Emma Navarro, Sofia Kenin, Sachia Vickery, Colombia's Emiliana Arango, Anastasia Potapova, Italy's Camila Giorgi, Egypt's Mayar Sherif
Organizations:
Melbourne, Guangzhou, Harriet Dart of Great Britain, Guadalajara, Akron, D.C, WTA, Victoria Azarenka, Thomson
Locations:
Melbourne, Australia, China, Czech Republic, Poland, Britain, Spain, Belgium, Harriet Dart of Great, Akron Hailey Baptiste, Washington, Guadalajara, Mexico, Russia, Belarus, United States