Last updated on .From the section Gymnastics

Biles, a 10-time world champion, tweeted this picture

Four-time Olympic champion Simone Biles has been admitted to hospital with a kidney stone on the eve of the World Gymnastics Championships in Doha.

The American, 21, is due to return to international competition after an 18-month break on Saturday when the women's qualification rounds start.

"Nothing like a late night ER visit less than 24 hrs before world championships," she wrote on Twitter. external-link

"This kidney stone can wait, doing it for my team."

Biles, a 10-time world champion, accompanied the post with a picture from her hospital bed.