TOKYO 鈥 Japan bagged skateboarding鈥檚 first ever gold medal and notched a surprise win in the pool on Sunday, in a day of high drama where 18-year-old Tunisian Ahmed Hafnaoui stunned swimming superpowers with victory in the men鈥檚 400m freestyle.

Skateboarder Yuto Horigome, who grew up in the Tokyo ward where the event is being held, took gold at the debut of a sport once seen as a symbol of counterculture. That followed surprise medal joy in the pool for Yui Ohashi in the 400m women鈥檚 medley.

The gold haul, which came after judoka Naohisa Takato won the host nation鈥檚 first gold on Saturday, offers organizers hope of boosting enthusiasm for the delayed Olympics among the Japanese public, who are laboring under a state of emergency in the capital amid elevated COVID-19 cases.

But the biggest shock of the day came when Tunisia鈥檚 Hafnaoui won the swimming event.

鈥淚 just can鈥檛 believe it. It鈥檚 a dream and it became true. It was great. It was my best race ever,鈥 Hafnaoui said after he produced a blistering finish to pip Australia鈥檚 Jack McLoughlin, with US swimmer Kieran Smith taking bronze.

The joy in the teenager鈥檚 face was in sharp contrast to the misery of Wimbledon champion Ash Barty upon her shock departure in the first round.

Britain鈥檚 twice Olympic champion Andy Murray didn鈥檛 even get that far. He pulled out of the tournament injured before his opening singles match.

The Australians got their moment in the pool in the last of the morning races when the Dolphins beat their own world record of 3:29.69 in the 4x100m women鈥檚 freestyle relay. Chase Kalisz delivered Team USA its first gold in the men鈥檚 400m medley. 鈥 Reuters