The pole vaulter is a dual Swedish-US citizen born and raised in the US, who has competed internationally for Sweden since 2015.
Duplantis was the only pole vaulter to clear over six metres, at which point he had already secured gold in the World Championships.
Shortly afterwards, he set a new championship record at 6.06 metres, but he wasn’t finished.
On his first attempt to clear the 6.21 world-record height, he failed, but on the second attempt, he cleared with a 8.2 centimetre margin over the bar – meaning a new world record.
The crowd at Hayward Field, where the championships were held, went wild as Duplantis sprinted to see his father and coach Greg Duplantis, himself a former pole vaulter, and embrace his Swedish girlfriend Desiré Inglander.
“That’s his best jump ever,” his father said.
“It is great, I cannot complain!” said Duplantis, whose new mark bettered his previous best by 1cm, set when winning gold at the World Indoor Championships in Belgrade in March.
It was his fifth world record, and third this year.
“Actually, I did not think about the record that much today,” he said.
“Usually, it is always somewhere in the back of my mind but today, I was really focused on the win and I really wanted to win the gold so badly. It was the medal I was missing.
“So when I was on this height, it was like everything came together and it happened from there.”