Daniel Wiffen and Mona McSharry are once again Ireland's main medal hopes at the World Aquatics Championships in Qatar, which get under way on Sunday.
The week-long meet is also an Olympic qualifier, with Ireland looking to add to the three swimmers who have already booked their tickets to Paris Games this summer.
Wiffen, McSharry and Ellen Walshe - who is not in Doha this week - have already pre-qualified and this meet and the Irish Olympic trials at the National Aquatic Centre in April represent the final opportunities for Olympic qualification.
Wiffen goes to Doha ranked second fastest in the 800m freestyle, an event in which he is the short course world record holder, and third fastest in the 1500m.
He will be the first Irish swimmer in action early on Sunday morning in the heats of the 400m freestyle, where he will come up against reigning Olympic champion Ahmed Hafnaoui of Tunisia.
Wiffen may use his opening event as a preparation for the 800m and 1500m later in the week, which will also feature Hafnaoui, who won double gold at last year's World Championships in Japan.
Ireland has never won a long course World Championships medal.
Wiffen finished fourth in both the 800m and 1500m freestyle in last year’s meet in Japan.
"I'm doing the three events but depending how it shapes up this week in Doha that might change for the Olympics," Wiffen told the BBC.
"And if I make a mistake at this World Championships, I've got six months until the Olympics to fix it.
"It's also the chance to tick another box. I mean, no Irish swimmer has ever won a medal at the World Championship long course and, dare I say it, no Irish swimmer has ever become a world champion and hopefully we can do that and be the first to do that too."
Wiffen will be joined in the pool on the opening day by double Olympian Shane Ryan, who is competing in the 50m butterfly, a non-Olympic event, and by Darragh Greene, who is bidding to make his second Games in his favoured event, the 100m breaststroke.
McSharry lines up in the 100m breaststroke heats on Monday.
The Sligo native, based at the University of Tennessee where she is finishing her studies in kinesiology, is the second fastest in the world in her main event at present.
McSharry has the Lithuanian Ruta Meilutyte, once coached by Jon Rudd, ahead of her in the rankings.
Meilutyte, a gold medallist in the 2012 London Games in the 100m breaststroke, announced her retirement in 2019 after missing three drugs tests and was given a two-year ban.
McSharry was fifth in the 100m breaststroke final in 2023, just 0.13 seconds off the podium and beaten by four previous Olympic gold medallists.
Those performances helped, along with Walshe (200m butterfly), to go under the qualifying standards for the Paris Olympics.
Ireland's other squad members in Doha are Victoria Catterson, Eoin Corby, Thomas Fannon, Conor Ferguson, Maria Godden, Max McCusker, Erin Riordan, Grace Davison and John Shortt.
Walshe, Ellie McCartney and Tokyo Olympian Danielle Hill are absentees from the Doha squad.
Irish competitors at World Swimming Championships
Victoria Catterson - 100m and 200m freestyle
Eoin Corby - 200m breaststroke
Thomas Fannon - 50m freestyle
Conor Ferguson - 50m and 100m backstroke
Maria Godden - 50m, 100m and 200m backstroke
Darragh Greene - 50m and 100m breaststroke
Max McCusker - 100m butterfly
Mona McSharry - 50m, 100m and 200m breaststroke
Erin Riordan - 50m freestyle
Shane Ryan - 100m freestyle and 50m butterfly
John Shortt - 200m backstroke
Daniel Wiffen - 400m, 800m and 1500m freestyle
Grace Davison - 4x100m relay squad
