Czech top seed Barbora Zahlavova Strycova, Swedish second seed Sofia Arvidsson and South African eighth seed Kevin Anderson were ousted Monday at a $1.32 million WTA and ATP event.
Dutch standout Michaella Krajicek defeated Strycova 6-1, 6-3 in 70 minutes to book a second-round meeting with US qualifier Alexa Glatch in the 32-player women's indoor tournament.
US lucky loser Alexandra Stevenson eliminated Arvidsson 6-3, 6-1 to book a second-round date with compatriot Coco Vandeweghe.
Strycova's ouster left Czech seventh seed Renta Voracova as the only seed player in her half of the draw following Sunday's ouster of US No. 8 Vania King and Russian No. 4 Alla Kudryavtseva.
In the first match of the men's event, Anderson was beaten 5-7, 6-3, 7-6 (7/4) by American Robert Kendruck, who will face either US wild card James Blake or Brazil's Ricardo Mello in the second round.
Also falling Monday was women's fifth seed Olga Govortsova of Belarus, who lost 6-3, 4-6, 6-4 to French qualifier Stephanie Foretz Gacon.
The last of Gacon's seven double faults handed Govortsova a break to pull even at 4-4 in the final set but the lone French player in the women's draw broke back and held to advance after two hours and 22 minutes.
British qualifier Heather Watson will face Gacon in the second round.
US third seed Melanie Oudin advanced with a 6-4, 6-0 victory over Russian Anastasia Pivovarova. She will next face another Russian, Evgeniya Rodina, who beat Croatian wild card Ajla Tomljanovic 1-6, 6-0, 7-6 (7/5).