Czech Karolina Muchova overcame illness to reach her second consecutive US Open semi-final with a 6-1 6-4 victory over Beatriz Haddad Maia.
Muchova left the court after winning the first set with ease, left the court at 2-1 and again at 3-2 in the second and was seen by the doctor and physio at 4-3.
The unseeded 28-year-old, who only returned to action in June after undergoing wrist surgery in February, will face either top seed Iga Swiatek or American sixth seed Jessica Pegula for a place in Saturday’s final.
“It was a weird match,” Muchova said. “I had some problems that I don’t want to comment on, but I had to run to the toilet and back all the time.
“Sorry if this bothered anyone, but I had no other choice.”
Haddad Maia also struggled and appeared to be in tears before receiving treatment from the doctor while trailing 5-3 in the second set.
