The ITF has moved Thursday's matches to a 3 p.m. start time.
Two-time gold-medal champion and partner Joe Salisbury suffer heart-breaking loss.
The heat was oppressive on Wednesday at Tokyo, and players were suffering.
Simone Biles said she was inspired by Naomi Osaka putting mental health first in pulling out of gymnastics team final.
Nine current Top-20 singles players are playing mixed in Tokyo.
The Japanese star says she should have been used to the pressure that she faced in Tokyo.
Women's Round of 16 and Men's third-round action will take place on Tuesday at the Olympics Games.
