Mona McSharry was unable to replicate her performance in the heats of the 100m breaststroke in the semi-finals at the World Aquatics Championships in Singapore, finishing sixth and missing out on a place in the final.
In the morning session, the Sligo woman clocked an impressive one minute 5.99 seconds, her sixth fastest time ever, and the leading time of all the qualifiers for the semi-finals.
The Olympic bronze medallist took to the blocks in lane four in the second semi-final, with world record holder Lilly King marooned out wide in lane eight at her final international meet.
McSharry was fourth at the turn, but flagged in the closing stages to record a time of 1:06.33 to finish as the 11th fastest semi-finalist as China's Olympic silver medallist Tang Qiantang hit the wall first in 1:05.87.
Kate Douglass of the USA leads the timesheet going into the final after winning the first semi-final in 1:05.49.
McSharry said: "It didn't feel too bad honestly. I probably felt a little bit better until the last 25 metres again and then it hurt like this morning.
"It's very hard to tell where you're at in the race for breaststroke, so I was just trying to get my hands on the wall, but sadly it's just not meant to be.
"That's just the way it goes sometimes, everyone's kind of feeling it out in the heats and I had a very good heat swim. I was very happy with that and it is important to be able to produce that in the morning so that's a great takeaway. I just didn't replicate it tonight."
Meanwhile, Ellen Walshe finished in eighth in the 200m individual medley final in a race won by Summer McIntosh.
Walshe did not trouble the leaders with a time of 2:11.57.
The Canadian came home in 2:06.69 to claim gold with USA's Alex Walsh in second and Mary-Sophie Harvey taking bronze.
Walshe was happy to be part of the event: "I think to be in my first world final tonight is a huge experience against some massive names.
"I'm a little bit disappointed, but I'll roll on to the next one."
Looking ahead to the 200m Butterfly heats on Wednesday, an event back on Walshe’s roster since earlier this year, she added: "I don't really know where it's going to be. I've never raced it internationally at this level so I'm excited to kind of see where I can get.
"I'm looking forward to it."
Evan Bailey produced the display of his life on his on his World Championships debut, with the National Centre Limerick swimmer equalling Jack McMillan’s 200m freestyle Irish record of 1:46.66 to progress to the semi-finals before being eliminated.
It was Bailey’s first time under 1:47:00, having come into the meet with a best time of 1:47.04 from the Irish Open in April.
The New Ross man, who recently turned 20, finished seventh in his heat and was 15th fastest overall.
A beaming Bailey said afterwards: "I'm absolutely delighted. I’ve had a lot of ups and downs this season. My training has been going really well and I’ve just been waiting for that one swim to happen.
"I’m absolutely delighted with it and it was there. I can't thank the people around me or my team-mates anymore, they've done probably more of the work than I have to help get me here, but the training group right now we have is unbelievable and all the boys push each other."
He unable to better it in the semi, coming home in 1:48.75 in 16th place overall.
Danielle Hill opened her championships in the 100m backstroke and touched the wall in 1:00.79 to finish fifth in her heat and 18th overall, meaning the Larne swimmer missed out on a place in the semi-finals.
John Shortt saw his qualification bid in the 100m backstroke end in the heats as he clocked 54.26 to finish ninth.
You can watch the action on Eurovision Sport
