Former US Open champion Bianca Andreescu left the court in a wheelchair at the Miami Open on Monday after retiring hurt from her last 16 match against Ekaterina Alexandrova.
After the first set was hit by a two-hour rain delay, Canadian Andreescu went down in the third game of the second, grabbing her left ankle.
Alexandrova advanced 7-6(0), 0-2 (retired).
"I'm just really sorry that it happened to (Andreescu)," Alexandrova said. "Seeing her on the court in so much pain, it's just painful to watch.
"You cannot help, you just can do nothing, which is terrible. And I think she's going to be fine soon, and I'm wishing for her speedy recovery."