Mark English dropped out of the 800 metres at the Cork City Sports and so missed out on an opportunity to qualify for the World Championships in Doha.
The Donegal competitor has a best of 1:46.96 this season and needs to make 1:45.80 to make the Worlds.
However English, he faded badly going down the back stretch at the CIT track, and stepped off the track with 200 metres to go.
American Isaiah Harris was victorious in the end, clocking 1:47.42.
Phil Healy was in action in both the 100m and 200m and finished fourth in both events.
In the shorter event, she clocked a time of 11.49, with victory going American Candace Hill in 11.37
Hill also took the 200 in 23.07, with Healy clocking 23.40.