Olympic champions Noah Lyles and Julien Alfred will take to the track in Tokyo on Saturday for heats of the 100m.
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Lyles will come under pressure from a top Jamaican duo seeking to break US dominance in the blue riband event.
Alfred meanwhile will look to bag another global title for St Lucia, her Olympic gold the first for the tiny Caribbean island.
AFP Sport looks at three elements of the men and women's 100m:
LYLES, ALFRED THE TARGETS
There is no doubt that Lyles and Alfred have touched down in the Japanese capital with targets on their backs.
Although Lyles had a delayed start to the season, both have tasted success on the Diamond League circuit.
Lyles outran Botswana's Olympic 200m champion Letsile Tebogo in that event in the Diamond League finals in Zurich last month.
It was a result the American said had left him "with a lot of energy" heading to Tokyo.
Alfred also notched up a morale-boosting win over 100m in Zurich and was in no doubt about expectations in Japan.
"I feel like I want to add another gold in my collection," Alfred said. "I am much fitter than before and also mentally, I am in the right place where I want to be."
THOMPSON LEADS THE HUNTERS
Kishane Thompson, who won Olympic 100m silver just five-thousandths of a second behind Lyles in Paris, could be the biggest threat to the American.
Thompson went sixth in the all-time list after running a world-leading 9.75 seconds this season.
Fellow Jamaican Oblique Seville has also notched up two victories over Lyles in the Diamond League.
Their form left sprint legend Usain Bolt in no doubt over who would top the podium on Sunday.
"There's no reason they shouldn't be 1-2 because they are at the top, fastest times in the world this year and they've been competing for a while," said Bolt.
"It's just about one of them executing and it should be fine."
Alfred will be targeted by a raft of sprinters from the US and Jamaican squads, not least American Melissa Jefferson-Wooden.
Jefferson-Wooden, 24, became the first woman since 2003 to win the 100-200m double at the US trials.
She has a personal best of 10.65 seconds, making her the joint fifth-fastest woman in history, and is the world-leading time this year.
"I know that I'm in great shape and that it's all about putting together the perfect race at the perfect time, when it matters the most, and that is at the world championships in Tokyo," she said.
TEBOGO AN UNLIKELY OUTSIDER
Botswana's Tebogo is seen as the likeliest candidate to gate-crash the US-Jamaican battle in the men's 100m.
The 22-year-old is a proven competitor over the shorter sprint and can be expected to be in the battle for a podium place.
He accused Lyles of "arrogance" after the 200m Olympic final, but insists he is content not to have chosen the American's outspoken style.
"For me, I choose to be out of the spotlight and then just my legs do the talking," Tebogo said in Tokyo.
It may seem odd to mention the name of Shelly-Ann Fraser-Pryce in the same sentence as the word outsider, but that is certainly the case in her career-closing world champs.
The 38-year-old Jamaican is a five-time world champion over 100m, and in the last worlds in Budapest in 2023 claimed bronze.
Advancing years means Fraser-Pryce will finally hang up her spikes after Tokyo, having spent an incredible 17 years as a dominant force in women's sprinting.
"I'm looking forward to just finishing the chapter and ending this career in a magnificent way," said the sprinter who has won three Olympic gold medals and 10 world titles, with a total of 25 Olympic and world medals to her name.
"And I'm sure it'll work out in Tokyo."
Another relative outsider is Sha'Carri Richardson, who is the defending world champion but whose life off the track sometimes detracts from her on-field ability.