Warholm, a 25-year-old former decathlete, became Norway’s first ever male track gold medallist with a dominant performance in 48.35 seconds, pushing American Olympic champion Kerron Clement (48.52) into third behind Turkey’s silver medallist Yasmani Copello (48.49).
"He is a talent and showed that today,” Clement admitted of his new Norwegian rival.
In the women’s one-lap race, Francis produced a strong late surge in the final 20 metres to take the gold away from Olympic champion Shaunae Miller-Uibo of the Bahamas and American Allyson Felix, one of the sport’s most successful athletes.
Miller-Uibo, who seemed to pull up with an injury in her final few strides could only finish fourth behind bronze medallist Felix as Francis clocked a personal best of 49.92 ahead of silver medallist Salwa Eid Naser of Bahrain.
Felix’s bronze medal still put her equal with Usain Bolt and Merlene Ottey as the winner of the most world medals – 14. No female athlete has won more golds than her nine titles, however.
Day six of the championships also saw Britain’s Mo Farah qualify for Saturday’s 5000m final with second place in his heat (13:30.18) as he chases a fifth consecutive 5000 and 10,000m double at a global championship.
But Farah warned home fans not to take anything for granted after Olympic champions Bolt and Elaine Thompson both failed to win gold in the sprints at the London Stadium this week.
“It ain't easy. You have seen that with Usain Bolt,” Farah said. “No-one is going to give it to you, no matter who you are. It would be pretty amazing to bow out with another double gold but these guys are coming for me. I have to be ready.”
Botswana’s Isaac Makwala, cleared by the IAAF to run in the men’s 200m after being declared medically fit to compete, qualified for Thursday’s final. Makwala, who had missed the 200 heats, ran an extra time trial on his own earlier in the evening to qualify for the semi-finals where he finished second in 20.14 for a direct qualification place.
South Africa’s Wayde van Niekerk, bidding for a 200-400 double, finished third in his heat in 20.28 but went through as one of the two fastest losers with Britain’s Nethaneel Mitchell-Blake (20.19). But Jamaica’s Yohan Blake failed to make the final with 20.52.
China’s Lijiao Gong threw 19.94m to win the women’s shot final, the first time a Chinese athlete has won the event for 24 years.