Woodford Green’s Dan Awde ran a personal best in the 400m in Clermont Florida on Saturday.
A time of 45.96 was enough to comfortably win the ‘B’ race and move Awde into fourth in the UK’s season rankings.
Awde, 25, has twice competed in the Olympics for Team GB, in both 2008 and 2012.
Tiffany Porter came fifth in the Drake Relays 100m hurdles with a time of 12.71.
Over a mile, Alex Cornwall placed ninth at Berkley, Califorina, in a time of 4.07.49.