Simone Biles' bid to launch a history-making goldrush at the Tokyo Olympics fell apart after a single vault on Tuesday night when the gymnast superstar pulled out during the team event, and her American teammates were beaten to the title by the Russians.

The late-night drama was a fitting end to a day which had begun under the threat of a storm and featured the loss of the face of these Games, tennis player Naomi Osaka.

America's silver team medal means Biles can no longer win six golds in Tokyo which, added to her haul of four from Rio, would have confirmed her status as the greatest gymnast of all time.

"After the performance I did I just didn't want to go on," Biles said.

USA Gymnastics said Biles had withdrawn because of a "medical issue", and would be assessed daily.

"Injury, no," she said. "Just a little injury to my pride."

While she could still, in theory, win five and match the current record, it seems unlikely.

Russian great Larisa Latynina won nine gymnastic Olympic golds in the 1950s and '60s. Only Michael Phelps, with his 23 swimming golds, has won more.

If Biles does win five here she would join four athletes on nine -- Latynina, swimmer Mark Spitz and track and field athletes Paavo Nurmi and Carl Lewis.

Osaka, who lit the Olympic cauldron on Friday to open the Games after a one-year postponement, looked out of sorts and never settled into a rhythm as she lost 6-1 6-4 in the third round to Czech Marketa Vondrousova.

Her departure left Japan without its best known global sporting figure in the Olympics, one whose multi-ethnic background contrasts with the image of an insular and male-dominated country that emerged in the run-up to the event.

"I think it's maybe because I haven't played in an Olympics before and for the first one to be here was a bit much," she said.

It was her first tournament since she pulled out of the French Open in May. The women's tennis tournament has now lost both of its top draw cards after Australia's world number one Ash Barty was beaten in the first round.

The Games are taking place under a state of emergency and without spectators, an unprecedented event in the history of the modern Olympics.

Tokyo reported 2,848 infections on Tuesday, in line with warnings from health experts that the summer would bring a rebound in COVID-19 cases due to increased mobility and the spread of variants.

Games organisers have reported a total of 155 cases associated with the Olympics, a tiny percentage given the tens of thousands of people who have come from abroad.

Tokyo's virus cases are counted separately from those reported in the Olympic village. Athletes and other officials who have travelled from abroad are separated from the public.

While Osaka was out, and Biles diminished, other competitors enjoyed better days.

Japan won their second straight gold in softball, beating the U.S. 2-0, and Brazil's Italo Ferreira and American Carissa Moore overcame challenging conditions in brilliant style to win historic first Olympic surfing gold medals.

In the women's triathlon, Flora Duffy, 33, achieved instant national hero status when she won Bermuda's first Olympic gold medal.

With about 63,000 residents, the British Overseas Territory in the North Atlantic Ocean became the smallest nation to win a Summer Olympic gold medal.

In the pool, Russian Evgeny Rylov broke a US.stranglehold on the men's 100m backstroke, while Tom Dean powered to gold in the men's 200m freestyle, heading a British one-two with Duncan Scott taking silver.