Croatia's Ivo Karlovic is recovering in hospital in Miami after being admitted with viral meningitis.
The 34-year-old's wife Alsi has, however, dismissed reports that her husband had suffered a stroke.
"Ivo did not have a stroke, as some outlets have stated; rather, he has viral meningitis," she said.
"We ask for privacy during his recovery process. We thank everyone for their support and well wishes."
Karlovic is well-known for his thundering serves but he has now slipped outside the world's top 100 from a career-high ranking of 14.
He caused a major upset back in 2003 when he beat defending champion Lleyton Hewitt at Wimbledon.
His last tournament appearance was at the Sarasota Challenger earlier this month.