Second seed Caroline Wozniacki eased into the second round of the US Open in brutally hot conditions in New York.
With temperatures in the mid-30s and high humidity, an extreme heat policy was introduced for the men at a grand slam for the first time, permitting a 10-minute break between the third and fourth sets of matches.
The women have had a policy for some time allowing a similar break between the second and third sets of matches.
Australian Open champion Wozniacki did not need such respite in her 6-3 6-2 victory over former US Open champion Sam Stosur.
Tenth seed Jelena Ostapenko had a much tougher time against Andrea Petkovic but eventually prevailed 6-4 4-6 7-5, while fifth seed Petra Kvitova, who has often struggled with the conditions at Flushing Meadows, will have been relieved to come through 6-1 6-4 against Yanina Wickmayer
