Widely considered the greatest gymnast of all time, Biles misjudged her landing on the vault - an event she has so often dominated - and a score of 13.766 was the worst in the opening rotation.

Biles was supposed to do an ‘Amanar’ - a vault that begins with a roundoff back handspring onto the vault followed by two-and-a-half twists.

However, she appeared to change her mind during the jump and only did one-and-a-half twists and stumbled as she landed on the mat.