Hosts Japan claim opening medal as athletes battle searing heat at World Championships in Tokyo

Japan celebrated a podium finish on the opening day of the World Athletics Championships in Tokyo as Hayato Katsuki took bronze in the men's 35km race walk, a curtain-raiser contested in oppressive heat and humidity that forced organisers to alter start times.

Canada's Evan Dunfee won the event and Brazil's Caio Bonfim placed second, while temperatures climbed to about 30C with humidity above 90% during the first morning session, prompting officials to move road race starts 30 minutes earlier. Dunfee described the two-and-a-half-hour contest as "absolutely brutal." Medical teams were on hand as several athletes showed the effects of the conditions.

Katsuki held on to a home podium to the delight of spectators inside Japan National Stadium and supporters lining the streets, marking a poignant moment for a host nation that missed the opportunity to cheer athletes at the same venue during the pandemic-delayed 2020 Olympics. World Athletics president Lord Coe said close to 500,000 tickets had been sold and that some night sessions were completely sold out.

The conditions proved punishing across the field. Britain's Cameron Curbishley, who finished 34th of 50 starters in the men's race, called it "definitely the hardest race I have ever done" and said the humidity made it a mission simply to finish. Japan's Masatora Kawano briefly held the lead during the race but was overtaken by the heat; he completed the course but collapsed after crossing the line and required assistance off the track in a wheelchair.

Spain's competitors showed strength across events: Maria Perez dominated the women's race walk and was lifted by teammates after her finish. Several events have had start times adjusted to reduce heat exposure; both the women's marathon scheduled for Sunday and the men's marathon on Monday were brought forward by 30 minutes to 07:30 local time (23:30 BST) amid forecasts of a heatwave pushing temperatures into the mid-30s later in the week.

Yuko Arimori, president of Japan Athletics and a former Olympic marathon runner, said the return of a major global event to Tokyo could help erase the memory of empty stands at the 2020 Games. "Sport isn't just about the athletes but about everyone getting energy from it and lifting each other up," she said. "I think this event will help us wipe away the emotions we felt back then and remind us what sport should be like."

School pupils and enthusiastic supporters contributed to a lively atmosphere inside the stadium for the preliminary rounds, which included heats of the 100 metres. Olympic and world champion Noah Lyles, preparing for the 100m rounds, urged fans to bring energy to the night sessions, saying he had been "really sad to not have the crowds there in 2021." He added: "When we get together we're going to hopefully make fireworks."

For some athletes the heat had immediate competitive consequences. Race-walking judges and medical staff monitored competitors closely during 16 laps of a 2km road loop, and team officials assisted exhausted athletes after they finished each circuit. Great Britain advanced in several events: its mixed 4x400m team qualified for the final as the second-fastest qualifier behind the United States, and Scott Lincoln became the first British man to make a world shot put final since 2009.

Organisers said they would continue to monitor weather forecasts and athlete welfare as the nine-day championships progress. With the competition returning to Tokyo five years after the city staged the pandemic-delayed Olympics, organisers and officials emphasised the importance of managing heat-related risks while delivering a well-attended global meet.