Ciara Mageean suffered a surprise defeat in the 800m at the DIY Senior Track and Field Championships at Santry, Dublin on Sunday.
The Portaferry girl finished second in 2:06.85, with Siobhan Eviston winning in a personal best time of 2:06.69.
Mageean bounced back to win a highly competitive 1500m in 4:16.36.
Northern Ireland record holder Amy Foster completed a women's sprint double in the 100m and 200m while Jason Smyth won the men's 100m in 10.52.
European Junior silver medallist Mageean was keen to set a personal best in the 800m and set a blistering pace in the opening 400m, going through in 57 seconds.
She was chased all the way by Laura Crowe but both athletes faded in the final 200m, allowing Eviston to capitalise.
Mageean took a tumble over the line to take second, with Crowe third.
Stephanie Reilly finished seven seconds behind Mageean in the 1500m.
Foster recorded a time of 23.74 in the 200m and 11.69 in the 100m.
Newcastle athlete Kerry Harty won the 3000m steeplechase in 10:23.29.
Paul Hession produced the performance of the championships to win the men's 200m in 20.51, achieving the A qualification standard for both the World Championships and next year's Olympic Games.
Derval O'Rourke secured her ninth national title, running 13.24 in the 100m hurdles.