Japanese star Naomi Osaka crashed out of the Tokyo Olympics tennis competition on Tuesday as Brazil's Italo Ferreira and America's Carissa Moore claimed the first-ever gold medals in surfing.
Osaka, who lit the Olympic cauldron in the opening ceremony, lost 6-1, 6-4 to Marketa Vondrousova after an error-strewn performance, ending her cherished dream of winning on home soil.
The 23-year-old -- one of the faces of the Tokyo Games -- had not played since May, when she walked out of the French Open saying media commitments were harming her mental health.
The second seed will be bitterly disappointed at missing out on a chance of Olympic gold, especially after the early exits of world number one Ashleigh Barty and third seed Aryna Sabalenka.
"How disappointed am I? I mean, I'm disappointed in every loss, but I feel like this one sucks more than the others," said the four-time Grand Slam-winner.
Asked what went wrong, she replied: "Everything -- if you watch the match then you would probably see. I feel like there's a lot of things that I counted on that I couldn't rely on today."
In the men's surfing competition Ferreira, who learned his trade standing on the foam box his father sold fish from, snapped his board on the first wave and had to wait in the sea for a replacement.
But he recovered to score 15.14 to Japanese opponent Kanoa Igarashi's 6.60 at Tsurigasaki Beach, around 100 kilometers (60 miles) east of Tokyo.
"It's one of the best days of my life for sure," said the Brazilian. "I was so nervous at the beginning but I just tried to surf and have fun because two months ago I was busy with training and thinking and dreaming and now I've got the gold medal."
US surfer Carissa Moore beat South Africa's Bianca Buitendag in the women's final.
- Bermuda glory -
Triathlete Flora Duffy won the first gold of the day in the women's event, making Bermuda the smallest territory or nation in terms of population to win a gold medal at a Summer Games.
For Duffy it was a welcome reward after persistent injuries and a diagnosis of anemia in 2013.
"I have achieved my dream of winning a gold medal, but also winning Bermuda's first gold medal," she said.
"It's bigger than me and that's a really cool moment. That was the longest kilometer of my life (the final one of the run)."
Elsewhere, swimming powerhouses Australia and the United States won one gold medal each in the morning pool session and are on three golds apiece.
Australian world-record holder Kaylee McKeown upstaged American arch-rival Regan Smith to claim the women's 100m Olympic backstroke crown as Russia and Britain also won golds.
McKeown flew through the water at the Tokyo Aquatic Center to touch in 57.47 seconds, a new Olympic record and only fractionally outside her own world best while Smith had to settle for bronze.
McKeown, who lost her father last year to brain cancer, said: "It's not necessarily what I've been through. Everyone has a journey of their own and it just so happens that mine's been a really tough one."
On a day of upsets, American women's 100m breaststroke world-record holder and defending champion Lilly King was beaten by 17-year-old compatriot Lydia Jacoby and teammate and defending 100m backstroke champion Ryan Murphy also tasted defeat.
Russian swimmer Evgeny Rylov took gold in the final, with Murphy pushed into third place.
Britain's Tom Dean came back from two bouts of coronavirus to edge out team-mate Duncan Scott and win the 200m freestyle.
- Biles pressure -
Later, all eyes will be on US gymnastics star Simone Biles in the women's team final as the 24-year-old four-time Olympic champion seeks to erase the memory of an uncharacteristically error-strewn qualifying competition.
The US women came to Tokyo as firm favorites but Biles admitted to feeling the pressure in an Instagram post on Monday, saying "I truly do feel like I have the weight of the world on my shoulders at times."
With spectators banned from the gymnastics and most events at the Games to protect the Japanese public from coronavirus, Biles does not have a crowd to inspire her.
But it would be a huge shock if she failed to win a fifth gold to kick off her attempt to equal or surpass Soviet great Larisa Latynina's record of nine gymnastics titles.
