Jamaican Oblique Seville put the United States on warning that they will have their work cut out for another world 100 metres sweep when he posted the fastest time of the first round on Saturday with an impressive 9.86 second run.
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Jamaica have not triumphed in the blue ribband event since the last of Usain Bolt's golds in 2015, with the US winning the three since then, including a podium sweep last year.
Seville's time matched his personal best, was the third-fastest in the world this year and brought him home ahead of defending champion and event favourite Fred Kerley.
The duo had to deal with a long delay before their heat, which then featured two false starts, and Kerley barely got out of second gear to come home in 9.99, watching the action on the big screen as he eased down.
"I am very surprised by that, I never expected it in the first round," said Seville, who finished fourth in last year's final.
"I've been through some dark places but this shows I'm on the way now and can run with the best and I've got much more to come. Being able to stay with Fred Kerley in the lane beside me was great. That was something I will carry to the semifinals.
"We can give those Americans a scare. The Jamaicans are coming, definitely."
American Noah Lyles won his heat in 9.95 seconds while easing up and running in lane nine. Former champion Christian Coleman also advanced safely but surprise US champion Cravont Charleston went out as he clocked 10.18 to finish fifth in his heat.
Lyles's time was initially flagged as 9.82 seconds but was soon adjusted to a more realistic number.
"I'm going to run sub-10 every round and get faster and faster and the final will be won in whatever time I run," said Lyles, the double world champion over 200 metres.
"I've said I can run 9.65 and I don't think anyone else can do it. But if they think they can then I'll be there on the line to beat them to it."
Muscular Kenyan Ferdinand Omanyala, second in the world rankings, who served a doping ban in 2017, also looked strong coming in just behind him in 9.97.
World leader Zharnel Hughes of Britain, who was disqualified for a false start in the Tokyo Olympic final, perhaps had that in mind as he was awfully slow out of the blocks in the opening heat. However, once he got into his running he picked off everyone in front of him to win the heat in 10 seconds dead.
Italian Lamont Marcell Jacobs, who has barely raced since his shock Tokyo Olympic victory, looked a touch heavy but came through for his best time of the year, 10.15, to scrape through in third place in his heat, won in 10.07 by Japan's Abdul Hakim Sani Brown.
South African Akani Simbine, who has finished fourth or fifth in the last five global championships, also looked good in winning his heat in 9.97.
The semifinals and final both take place on Sunday evening.