Daniel Wiffen, John Shortt, Mona McSharry and Ellie McCartney progress at European Championships

The performance saw the Olympic champion in the event finish third in his heat and third fastest overall heading into the medal race, behind Hungary's Zalan Sarkany (7:42.34) and Germany's Johannes Liebmann (7:41.87).

"Unbelievable, I'm so happy," said Wiffen.

"Coming into this I went 7:48 at the Commonwealth Games to get fourth place and I didn't know what shape I was going to be in or whether I'd make the final. To drop a time like that after a week of resting post-Commonwealth Games, I'm really happy. I even went out really quick through 400m, so it's a good sign for the final."

There was further cause for celebration for Team Ireland as the Mixed 4x100m Medley Relay set a new Irish Record.

Earlier in the morning Olympic bronze medallist Mona McSharry produced an impressive morning swim to qualify for the 100m Breaststroke semi-finals in a season's best 1:05.97.

The Sligo swimmer was one of just two athletes to break the 1:06 barrier, alongside Great Britain's Angharad Evans, who set a Championship Record of 1:05.45. McSharry and Evans progressed as the top two seeds overall.

In the same race, Commonwealth Games bronze medallist (200m Breaststroke) Ellie McCartney advanced to the semi-finals in sixteenth place with a time of 1:07.96.

"I'm happy. Having gone 1:05 before, it's funny because I look at that and think it's a good morning swim. I'm happy with it and hopefully I can build on it tonight and go even faster," said McSharry.

John Shortt also progressed comfortably, booking his place in the 200m Backstroke semi-final in 1:56.50 after finishing fourth in a high-quality heat.

The National Centre Limerick swimmer was up against elite company, led by France's Nathan Muratory, who set a World and European Junior Record of 1:54.87, alongside Olympic champion Hubert Kos (1:55.37) and Olympic bronze medallist Roman Mityukov (1:55.91).

"That was good. Going into your main event so early in the competition there's always a bit of uncertainty," said Shortt.

"I stuck to my routine, stayed relaxed and just focused on getting the job done. It felt like a pretty good swim, so hopefully there's a bit more to come tonight."

On Tuesday evening, Jack Kelly will be first on the blocks as he races the 100m Breaststroke Final at 17:48 (IRL). Mona McSharry and Ellie McCartney go in Semi-Final one of the 100m Breaststroke at 17:54 (IRL) and John Shortt competes in the first of the 200m Backstroke semi-finals at 18.03 (IRL).

One of the standout performances of the morning came from Ireland's Mixed 4x100m Medley Relay team. Lottie Cullen, Darragh Greene, Jack Cassin and Grace Davison combined to clock 3:48.34, breaking the national record of 3:49.08 that had stood since 2021 and finishing eleventh overall.

Ellen Walshe opened her championship campaign in the 50m Butterfly, setting a personal best of 26.62 as the Olympic finalist fine-tuned preparations for Wednesday's 400m Individual Medley. Rosalie Phelan (27.36) and Alana Burns Atkin (28.01) also competed in the event, with Burns Atkin making her senior international debut for Ireland.

In the men's 800m Freestyle, Nathan Wiffen joined his twin brother Daniel in the heats and dipped under eight minutes for the first time this season, clocking 7:57.08, just over two seconds outside his lifetime best of 7:54.60. Liam Custer also recorded a season's best of 8:06.89, just 0.72 seconds shy of his personal best.

The men's 100m Freestyle heats saw Evan Bailey narrowly miss his career best, touching in 48.97 after entering with a 48.94. Matthew Hamilton posted a time of 50.45.