Johanna Konta will miss this week's clay-court season-opener in Charleston because of a shoulder injury and illness.
The 25-year-old has revealed she was battling both during her run to victory in last week's Miami Open.
Now seventh in the world, she would have been the highest-ranking player competing in this week's event.
"[Charleston] is a great tournament and I was really looking forward to taking part," said Konta.
"I was battling a slight shoulder injury and sickness during Miami which has taken hold since the end of the tournament."
Konta beat Denmark's former world number one Caroline Wozniacki 6-4 6-3 on Sunday to become the first British woman to win the Miami Open.