Emma Raducanu will "come back better prepared and stronger" after being forced to retire in the Wimbledon fourth round, her Billie Jean King Cup captain Anne Keothavong says.
She had only made her WTA Tour debut in June, but beat two top-50 players on her way to the last 16.
"She's OK. She's going to be fine," Keothavong told BBC Breakfast.
No details have been released about what caused the breathing difficulties or the nature of them.
Former British number one Keothavong added: "Last night I saw her leave the club. It was a difficult situation for her to be in, and for everyone to witness, but she'll be just fine.