Olympic 100 and 200m champion Elaine Thompson-Herah is eager to gauge her speed ahead of the world championships in Saturday's Prefontaine Classic.
The Jamaican, who has been dogged by a lingering Achilles injury, dropped out of the Birmingham Diamond League meet earlier this month citing discomfort in training.
It has caused occasional interruptions but says it won't stop her from competing.
"My injury doesn't require surgery and it's very frustrating - some days I have to sit on the side, not able to train and then I had a rotator, shoulder, dislocation," she said.
"I am so determined to compete because I want to see where I'm at in the season right now ... I'm a tough cookie."
The Eugene Diamond League meet marks her first return to Hayward Field since producing the second-fastest 100m of all time - 10.54 seconds - weeks after completing a 100-200 double for a second successive Olympics in Tokyo.
"It was surprising - due to the fact that I came off a championship, which I doubled up," she said.
"I always tell people that whenever I feel sluggish or slow, that's when I run the fastest time and honestly I didn't feel that fast and I think I like to surprise myself."
Thompson-Herah will compete alongside American Sha'Carri Richardson, Britain's 200m world champion Dina Asher-Smith and felow Jamaican Shericka Jackson, with whom she also picked up gold in the 4x100 metres relay in Tokyo.
Absent from the 100m field is compatriot and world champion Shelly-Ann Fraser-Pryce, who opted to run the 200m in Eugene.
The twice Olympic gold medallist took silver in the 100m and just missed out on the podium in the 200m in Tokyo.
But she left open the possibility of attempting a double at the world championships in Oregon in July.
"Last year doubling was hard. I thought it would be easy but it was very hard," said the 35-year-old, who produced a world-leading 10.67 seconds to win the 100m at the Kip Keino Classic earlier this month.
"I think I've doubled three times now at the championships ... I'm thinking about it but it depends on how you just feel."
Australia's Nicola Olyslagers will compete in the women's high jump final with compatriot Charlie Hunter lining up in the men's 1500m final.
Matthew Ramsden and Brett Robinson are in the men's 5000m final, with Jessica Hull chasing glory in the women's 1500m and Oliver Hoare in the one-mile men.