NAGOYA, Japan — The first gold medal of the 20th Asian Games was won on Sunday by host nation Japan as a 13-year-old swimmer from China started in blistering form on the opening day of the multisports extravaganza. Japan's Takumi Hojo won the men's individual triathlon in Gamagori city near Nagoya, with China's Zhang Xirui second and Kazakhstan's Arlan Zhanabay taking bronze. It was the first of 469 gold medals to be awarded at a two-week spectacle that has more athletes than the Olympics. Action also began in the swimming pool, where Yu Zidi, who does not turn 14 until next month, was fastest by far in the women's 200m butterfly heats. Teenager Yu was almost 2.70 seconds quicker than compatriot Chang Mohan and will be a hot favorite to take her first major gold in Sunday evening's final. The Games were officially declared open on Saturday by Japan's Emperor Naruhito, but there were a large number of empty seats at the 30,000-capacity stadium in Nagoya. It sounded the starting pistol on two weeks of intense action as the continent's finest athletes compete in more than 40 sports before the curtain comes down on Oct. 4. The event in Nagoya and Aichi prefecture has 2028 Olympics places up for grabs but has been dogged by a series of problems in the build-up. Accommodating more than 11,000 athletes and 6,000 officials has stretched organizers to the limit after they decided not to have a traditional athletes' village to save money. Competitors instead are staying in a combination of temporary container-style huts, hotels and the cruise ship Costa Serena. There was a record deluge last week, which flooded parts of Nagoya and a typhoon is due to skirt the area on Sunday night, threatening further disruption. Some athletes were left stranded at the airport when transport failed to turn up and several teams have complained about the quality of the huts, including the beds being too short. And Games organizers were forced to offer "deepest apologies" after North Korea's national anthem was played on Friday for South Korea's men's hockey team before a preliminary match.