Defending champion Sofia Arvidsson of Sweden and top seed Kirsten Flipkens of Belgium advanced to the second round of the $1.58 million ATP and WTA US Indoor Championships with triumphs Monday.
Second seed Arvidsson beat Slovakian qualifier Jana Cepelova 6-4, 6-4 while Flipkens eliminated 2007 Memphis runner-up Shahar Peer of Israel 6-2, 6-2.
Arvidsson, who also won at Memphis in 2006, defeated New Zealand's Marina Erakovic in last year's final. This year, Arvidsson will face Erakovic again in the second round after Erakovic beat Germany's Annika Beck 4-6, 7-6 (8/6), 6-4.
Next up for Flipkens will be Ukraine's Lesia Tsurenko, who defeated US qualifier Maria Sanchez 6-2, 6-4.
American Jamie Hampton downed Spanish wild card Garbine Muguruza 6-3, 6-3 to book a second round date with compatriot Coco Vandeweghe.
French eighth seed Kristina Mladenovic opened with a 6-3, 6-1 victory over US wildcard Courtney Collins and will next face another US wildcard, Victoria Duval, who fought back to defeat Sweden's Johanna Larsson 3-6, 6-1, 6-3.
The men's event began with Croatian top seed Marin Cilic rallying to beat countryman Ivan Dodig 4-6, 6-2, 6-3 and Poland's Lukasz Kubot outlasting American Ryan Harrison 6-4, 6-7 (4/7), 7-6 (7/2).