Noah Lyles has vowed to beat the times of sprint legend Usain Bolt, but the American was below his best when capturing the 200 metres title at the World Athletics Championships.
Lyles was unconvincing in claiming gold in Doha, needing a late surge to justify his status as the clear favourite.
His compatriot Donavan Brazier produced a stunning performance to win the 800m, while Britain's Dina Asher-Smith will go into the women's 200m final as the athlete to beat after she laid down a big marker in the semi-finals.
The field events, meanwhile, produced no shortage of drama.
LYLES LEAVES IT LATE
Lyles was expected to take gold in the 200m but few would have predicted the manner of his victory.
The American was behind going into the straight as Britain's Adam Gemili led after a great start and an excellent bend.
However, Lyles turned on the jets in the final 100m and edged to victory in 19.83 seconds. Canadian Andre De Grasse added to his Olympic silver by coming home in second, ahead of training partner Alex Quinonez of Ecuador.
A devastated Gemili was fourth, again narrowly missing out on a major individual medal after finishing in the same position at the Olympics three years ago.
BRAZIER BREAKS RECORDS
Brazier's victory could hardly have looked more dominant as he burst clear with 300m to go, and his 800m championship record of 1:42:34 also set a US record.
Amel Tuka of Bosnia-Herzegovina was over a second behind in silver, with Ferguson Cheruiyot Rotich taking bronze for Kenya.
"I really had to dig deep for that one," Brazier told BBC Sport. "Little bit of a target on my back now [ahead of the Olympics]. I'd rather have it than not have it."
DINA LAYS DOWN MARKER
With Olympic champion Elaine Thompson, Shelly-Ann Fraser-Pryce, Marie-Josee Ta Lou and 2017 world champion Dafne Schippers all having pulled out of the 200m, Asher-Smith is the clear favourite.
The European champion was a class above in her semi-final and the fastest qualifier for the final as she won in 22.16 seconds.
With Brittany Brown the next fastest qualifier in 22.46 seconds, it will take a significant tunaround to deny the 100m silver medallist the 200m title.
KENDRICKS DENIES DUPLANTIS
The men's pole vault final proved a thriller as Sam Kendricks successfully defended his title, becoming the first man since Sergey Bubka to win multiple world championship golds in the discipline.
Kendricks was run extremely close by Swedish teenager Armand Duplantis. Both men cleared 5.97 metres on the final attempt but neither could manage 6.02m.
That meant Kendricks retained the title on countback, courtesy of clearing 5.92 with his first attempt, though Duplantis did not seem disappointed with silver. He and Kendricks, along with bronze medallist Piotr Lisek, backflipped on to the mat after the result was decided.
Meanwhile, in the women's javelin, Australia's Kelsey Lee-Barber took gold with her final attempt, a throw of 66.56m, denying Liu Shiying and Lyu Huihui a Chinese one-two.