Northern Ireland swimmer Melanie Nocher set a new personal best in the 200 metres freestyle heats at the World Championships in Shanghai.
Nocher's time of 2:01.33 cut .02secs off her previous mark and left her in 31st place.
Like British duo, Rebecca Adlington and Jo Jackson, Nocher did not progress to the semi-finals.
Barry Murphy just missed out on a place in the 50m breaststroke semi-finals as he was 18th in 28.13.
Murphy's final event of the championships will be Friday's 50m freestyle.
On Monday, Sycerika McMahon set an Irish record for the 100 metres breaststroke in Shanghai.
McMahon clocked 1:09.91 but it was not enough to earn a semi-final place as she came 27th in the timings.
The 16-year-old Leander club member from Portaferry goes in Thursday's 4x200 freestyle relay and the 50m breaststroke on Saturday.
Nocher was 37th overall in the heats for the 100m backstroke heats on Monday.
It was just over a second outside the Belfast woman's personal best.
Ireland's top swimmer Grainne Murphy just missed out on a place in the 1500m freestyle final.
The Wexford woman, who took silver in the event at last year's European Long Course Championships, won her heat but finished 10th in the overall standings.