Top-seeded American Madison Keys overcame an inconsistent serve to reach the second round of the Strasbourg International with a 6-4, 6-3 win against countrywoman Christina McHale on Monday.

Keys had four aces but also double-faulted twice, dropped her serve twice in the first set and saved all three break points in the second set. The 20-year-old Keys next faces Croatian veteran Mirjana Lucic-Baroni.

American Alison Riske also reached the second round after upsetting fifth-seeded Zarina Diyas of Kazakhstan 7-5, 4-6, 6-1.

Also, second-seeded Jelena Jankovic of Serbia advanced with a 7-6 (6), 6-3 win against Irina Falconi, third-seeded Samantha Stosur of Australia beat Monica Puig 6-0, 6-3, No. 4 Alize Cornet of France won 6-3, 6-3 against Qiang Wang, and No. 6 Coco Vandeweghe beat Oceane Dodin 7-6 (3), 7-5.