Britain's Adelle Tracey beat compatriot Jemma Reekie by one hundredth of a second to win the women's 800m at the USATF Grand Prix.
Tracey clocked two minutes 03.25 seconds in Eugene, Oregon.
Laura Muir won the women's 1500m in four minutes 01.54 seconds, finishing more than two seconds clear of second-placed Helen Schlachtenhaufen.
"I've never done a race gun to tape by myself. I know I'm in really good shape so I'm pleased," said Muir.
"I wanted to try and run really hard right from the start. The wind was quite tough working by myself."
Two-time British Olympian Eilish McColgan won the women's 5,000m in 14 minutes 52.44 seconds, while American Isaac Updike ran the fastest time in the world this year to win the men's 3,000m steeplechase in a personal-best eight minutes 17.74 seconds.
American six-time Olympic champion and 13-time world champion Allyson Felix, 35, finished seventh in the women's 100m in 11.30 seconds, as she aims for Olympic qualification in the 200m.
American Trayvon Bromell won the men's 100m in 10.01 seconds, with compatriot Noah Lyles second in 10.17.
Reigning Olympic champion Shaunae Miller-Uibo of the Bahamas ran a world-leading time of 49.08 seconds to win the women's 400m.