Dina Asher-Smith eased into the 100 metres semi-finals at the World Championships as Jamaica's Shelly-Ann Fraser-Pryce let her know just how fast she needs to run to take gold.
Great Britain's European champion ran 10.96 seconds to win her heat in Doha to safely progress to Sunday's semi-finals.
Asher-Smith was the third fastest qualifier on Saturday and remained on course in her bid to win medals in the 100m, 200m and 4x100m relay.
But double Olympic champion Fraser-Pryce sent out an ominous warning by running 10.80secs - the fastest women's 100m heat time in World Championship history.
The Jamaican, who missed the Worlds in London in 2017 as she had a baby that summer, said: "It was a good run. I'm excited to be back.
"I tried to execute the best way possible because my technique is not the best.
"There are so many talented women and it is a blessing to do it again."
Marie-Josee Ta Lou, who won silver two years ago, clocked a personal best of 10.85s to qualify second fastest.
Reigning Olympic champion Elaine Thompson ran 11.14, with all the favourites reaching the next round.
Great Britain's Daryll Neita qualified in 11.12, a personal best, but Asha Philip missed out after running 11.35 to finish sixth in her heat.
Imani Lansiquot qualified as the final fastest loser in 11.31.
Neita said: "I am at the World Championships. This is it. We have trained forever for this. It was all about me executing what I can do.
"I remained calm, and I am really happy the heat is done. It's a PB.
"I am really happy. I looked at my heat and thought, 'Oh, I have to run really well here.' It was great to be second to a 10.8 (Fraser-Pryce)."