The 21-year-old went to the emergency room overnight where she was treated for a kidney stone, but showed no ill-effects at the Aspire Dome.

Biles, already a 10-time world champion and a quadruple Olympic gold medallist, competed as women's qualification for the team, all-around and individual apparatus finals took centre stage.

She helped the Americans top the team standings and also led the way in the all-around, floor, beam and vault competitions.

Her all-around total of 60.965 sees her boast a huge lead over second-placed compatriot and defending world champion Morgan Hurd, who sits on 56.465.

Japan's Mai Murakami is third on 55.632.

Biles even introduced a new vault - a Yurchenko half-on, double-twisting layout handspring front off - as she led the way on that apparatus on 15.666.

She topped the beam on 14.800 and floor on 15.333.

Nina Derwael of Belgium was the only gymnast to get the better of Biles, topping the uneven bars on 15.066 as the American came second on 14.866.

"It's been crazy, I got back from the emergency about 1am and they found I had a kidney stone," Biles told BBC Sport.

"But the pain is pretty okay right now.

"I'm excited how today went and we'll keep good spirits for the team final and all-around."

Qualification will continue tomorrow in women's events with China and Russia joining the fray.

The top eight gymnasts advance to the individual finals, with a limit of two gymnasts per nation in any one event.

The three medal-winning nations in the team final earn berths to the 2020 Olympic Games in Tokyo.

Biles has helped the US lead so far on 174.429, with Japan second on 162.180 and Germany third on 161.071.