British pair Sonay Kartal and Katie Boulter were knocked out in the US Open first round as conditions heated up in New York.
Kartal, who has been managing a knee niggle in recent months, suffered physically in a 6-3 1-6 6-1 defeat against Brazilian 18th seed Beatriz Haddad Maia.
Boulter, 29, lost 6-4 6-4 to Ukrainian 27th seed Marta Kostyuk as she was unable to turn around her Grand Slam struggles.
A bizarre deciding set saw a struggling Kartal trail 3-0 before being handed a lifeline when Haddad Maia's movement also became hampered - seemingly down to cramp.