Kipyegon arrived in Budapest in fine form having recently beaten world records for the 1500m, 5,000m and mile, and added to her successes with a dominant victory in 3min 54.87sec.

"This is a great season for me," she reflected afterwards.

"To break the world records and become a world champion here, to defend my title.

"I told myself, 'you are the strongest and just keep going'.

"I was chasing a history today and I was chasing this title.

"I have done it."

Diribe Welteji of Ethiopia took silver in 3:55.69 for a first medal at the World Championships, and 2019 world champion Sifan Hassan of The Netherlands came through in third in 3:56.00.

Kipyegon's success came in a flurry of medal action, which began with American Laulauga Tausaga, a surprise winner in the women's discus throw.

She threw a personal best 69.49 metres on her fifth attempt to propel herself into top spot, usurping compatriot and Olympic champion Valarie Allman, who had led with 69.23m but could not reply to Tausaga.

"I don't know if I have a fairy godmother or something, or my ancestors had some say in it, but I was able to do something tonight that I didn't think was possible yet," Tausaga admitted.

China's defending champion Feng Bin took bronze with a season's best 68.20m, Jorinde van Klinken of The Netherlands placing fourth with 67.20m and Croatia's double Olympic and world champion Sandra Perković fifth with 66.57m.

Joint-Olympic champion Gianmarco Tamberi of Italy could not contain his joy as he claimed men's high jump gold for the first time at the World Championships with a world-leading 2.36m.

Tamberi knew he had secured gold when JuVaughn Harrison of the United States failed on his third attempt at 2.38m, and had already began celebrating when he made an unsuccessful final try at 2.40m.

A run of three consecutive World Championships golds for Qatar's Mutaz Essa Barshim, with whom Tamberi shared Olympic gold at Tokyo 2020, came to an end, but he took bronze with a 2.33m first-time clearance.

Soufiane El Bakkali of Morocco was the day's other winner, extending his domination of the men's 3,000 metres steeplechase by defending his title in 8:03.53.

Ethiopia's Lamecha Girma had to settle for silver in 8:05.44 behind El Bakkali as he did at the Tokyo 2020 Olympics and the World Championships in Eugene last year, and Abraham Kibiwot of Kenya recovered from a stumble on the final lap to take bronze in 8;11.98.

Britain's Matthew Hudson-Smith also broke a 36-year men's 400m European record held by East Germany's Thomas Schönlebe with a 44.26sec run in the semi-final in which he slowed down for the final stages, and the competition is now wide open after the Bahamas' Olympic champion Steven Gardiner pulled up injured in his semi-final.

Olympic and world champion Emmanuel Korir of Kenya failed to progress through the men's 800m heats after a season hampered by injury.

Nigeria's defending champion Tobi Amusan - who was only cleared to compete on Thursday (August 17) after a Disciplinary Panel ruled she had not committed an anti-doping rule violation after being charged with whereabouts failures - made a confident start by winning her 100m hurdles heat in 12.48.

The World Athletics Championships is set to continue tomorrow, with finals in the women's pole vault, men's 1500m, women's 400m and men's 400m hurdles.