Istomin downed wildcard Duckworth and will now face fourth seed Fernando Verdasco, who received a first-round bye.
Fifth seed Florian Mayer progressed with a straightforward 6-1 6-2 victory over qualifier Joao Sousa, while number eight Marcel Granollers came from behind to beat wildcard Matthew Ebden 5-7 7-5 6-1.
Julien Benneteau progressed with a 6-3 5-7 6-2 win over Pablo Andujar.
In the women's competition, two seeds were defeated in the first round with number six Samantha Stosur falling 6-3 6-7 (7-9) 6-4 to China's Jie Zheng and eighth seed Nadia Petrova losing 7-5 7-5 to Roberta Vinci of Italy.
Third seed Sara Errani had no problems in dispatching qualifier Karolina Pliskova 6-1 6-3, while fourth seed Li Na beat Christina McHale 7-6 (7-2) 7-5.
Three qualifiers are through to the second round with Ayumi Morita beating Daniela Hantuchova 1-6 6-3 6-3, Madison Keys topping Lucie Safarova 6-2 6-1 and Kimiko Date-Krumm beating Casey Dellacqua 6-4 6-1.
Jelena Jankovic also progressed with a 6-2 7-6 (7-5) victory over Tamira Paszek.