Defending champion Dina Asher-Smith faces a battle to retain her 200m title at the World Championships.
Jamaica duo Shericka Jackson and Shelly-Ann Fraser-Pryce fired their warnings in Tuesday’s semi-final in Eugene.
Jackson’s time of 21.68 seconds and Fraser-Pryce’s run of 21.82 seconds set the tone.
Asher-Smith ran a season’s best of 21.96 seconds to finish behind Tamara Clark of the USA in her semi and reach Thursday’s final.
“I am really happy with that,” she said. “We knew we had to run this very well so I was really happy to get second. I didn’t actually know if I came first or third so I was just waiting.
“We came here sharp because it is the World Championships, we are always ready to go and that is just part of the job – navigating your way through the rounds and making it into the final. That is also part of the skill.
“I’m happy that we’ve got a day break so I can rest, recuperate, focus and get ready to go again, just a bit faster.”
Jackson holds the world lead of 21.55 seconds with Asher-Smith likely to need to smash her own British record of 21.88 seconds which she posted winning in Doha three years ago to stand a chance of keeping her title.
Jackson’s effort was the second fastest time in the world this year and 12th quickest in history. Sunday’s 100m champion Fraser-Pryce impressed again despite slowing down before the line.
Asher-Smith came fourth, behind a Jamaica clean sweep, in the 100m final on Sunday despite equalling her British record of 10.83 seconds.
Great Britain captain Nethaneel Mitchell-Blake ran 20.30 seconds in the men’s 200m semi-final and failed to progress with Joe Ferguson also out. New 100m champion Fred Kerley appeared to suffer a hamstring injury in the same heat and was knocked out.
Mitchell-Blake said: “Championships are gruelling. I can’t complain about the race load because some people have doubled. It’s nice to be in an environment again where I’m competing with the best and I feel like my best is yet to come.”
Jessie Knight reached the semi-final of the 400m hurdles but there was no place for Lina Nielsen.
Brazil’s Alison Dos Santos took the 400m hurdles crown, Australia’s Eleanor Patterson won the women’s high jump title and Slovenia’s Kristjan Ceh the men’s discus.
