British number one Elena Baltacha progressed to the second round of the Texas Open with a 6-2 6-1 win over Barbora Zahlavova Strycova.
The 28-year-old took less than 80 minutes to beat the Czech player and will now face German Julia Goerges.
Swede Sofia Arvidsson beat fourth seed Yanina Wickmayer after the Belgian was forced to retire in the third set of her match with the scores 4-6 6-0 1-0.
Fifth seed Sabine Lisicki defeated India's Sania Mirza 6-3 6-0.
Baltacha said: "I'm so pleased with that win.
"I felt I was solid all the way through and that's a good sign, especially against such a good player.
"Conditions have been really hot here so it's really good preparation for the US Open because it can get humid in New York. I'm definitely looking forward to playing Georges tomorrow because she's a talented girl and it's another good challenge for me."