Pictures of Williams leaving the tournament grounds following her match seemed to show that she was "walking OK" after receiving treatment.
Although the tennis legend, who turns 40 in September, has yet to reveal her future plans, her coach, Patrick Mouratoglou, appeared to suggest that they'd continue to work together.
"Serena trained hard. She was ready. She wanted it with all her heart. But unfortunately, her foot slipped and her body, as it reacted, broke down," Mouratoglou wrote on Instagram. "It is heartbreaking but there is nothing we can do about it, except working and trying again."
And, in a potential message of hope, he appeared to look to the future, simply writing: "See you soon."