Britain's Andy Murray and Heather Watson both progressed at the Miami Open on a day when players struggled in the heat.
Murray played in cooler temperatures as he beat Uzbekistan's Denis Istomin 6-3 7-5 in the evening session.
Watson had earlier fought back to beat Belgian Yanina Wickmayer 3-6 7-5 6-3 over two-and-a-half hours.
Fellow Briton Aljaz Bedene was forced out with a wrist injury, while Jamie Murray lost in the doubles.
Murray wins despite rogue ball
Having waited until the final session of day six to play his first match, second seed Murray saw off world number 76 Istomin in one hour and 38 minutes.