Daniel Wiffen oozed class in winning his heat of the men's 800m freestyle, advancing to Tuesday's final in fine style.
Wiffen, world champion in the event, came home in a time of seven minutes 41.53 seconds, the fastest of those making it through to the medal race.
The Armagh native said he was "very happy" with his performance in the semi-final.
"It was very close to my World Championship winning time that I only did like six months ago, and it felt a hell of a lot easier than that one so I'm happy. Happy with the pace and happy with the fitness," Wiffen said.
"Can’t ask for anymore. I love a centre lane, it’s my favourite lane. But we just have to wait and see tomorrow night, I guess.
He added: "It’s all about this 36-hour recovery period and that’s what I’ve got to get right."
However, early in the race he faced stiff competition from two Australian swimmers - Elijah Winnington and Samuel Short - before easing past them into first place.
"They love to take it out hard. Both of them have done the 400m on the first day so I’m sure they’re a bit tired but I just swam it the way I swim it and that’s the middle half and that’s why I took the reins about 500m," he said.
Walking out ahead of the race, Wiffen admitted to feeling nervous but said any nerves quickly disappeared after the first 100m.
But with not much difference in the qualifying times of the eight finalists, Wiffen expects a tight race.
"Everybody’s got a lane in the final and anybody can win from anywhere, so I’ll be well aware of every lane. I’m looking forward to the final.
"I said I wanted a medal and I’ll be coming away with one eventually at some point and I just can’t wait to race again. Honestly, I love that," he said.
Wiffen said he has enjoyed his Paris experience thus far, but added that the food in the Olympic Village is "terrible".
"The food is a bit terrible, honestly, in the village. Everything else is class; I love the flats, I love everything - the team atmosphere - it’s great. I love being part of Team Ireland.
"There is quite a lot of Irish support here and I’m really looking forward to the final because I heard a lot of people are coming so it’ll be good to see," he said.
Wiffen said he was eagerly anticipating what could be a big night in the pool for Ireland.
"Sadly, I won’t be able to watch it personally because I’ll be doing my recovery, but I’ll be 100% cheering on from the stream from back in the hotel but good luck to them."
Ellen Walshe produced a strong finish to grab fourth place in her heat and a spot in the final of the 400m individual medley tonight.
The Templeogue competitor came home in a time of 4:39.97 seconds, placing her seventh overall, and through to the final.
A strong breaststroke leg was key to the 22-year-old advancing.
Canadian Summer McIntosh, one of the favourites for the event, won Walshe's heat in a time of 4:37.35.
Walshe said the race was "a bit surreal" and to qualify for the final was a "dream".
"It's been a long process, I was ninth at World’s last year in the 200 and I guess you either come back fighting or it’s going to hurt.
"Today I had an opportunity to make it into that final and I’m delighted to say I’ll be in the final tonight."
"I just want to get out stronger, enjoy every minute of it. I don't know how long I have left and I don’t know if I’ll ever be in another Olympic final so I’m just going to go out there, be proud and hopefully have a good race," she added.
The 400m IM final is scheduled for 7.30pm this evening.
Danielle Hill also come home fourth in the heats of the women's 100m backstroke, clocking 1:00.04, good enough to see her make the semis.
Hill said in the aftermath of the race and her qualification for the semi-final that she was "feeling very emotional ... but I honestly couldn't be happier".
"It’s been a long journey to get here and all I wanted to do was come out here, enjoy the moment for what it was."
She added that it was "so special" to be in a semi-final in the Olympic Games and that she wanted to make her family and friends who were in attendance proud.
"Even to get here as a two-time Olympian is incredible so now to be in a position where I’m progressing through the rounds is a credit to Team Larne and everything they have done for me and been through with me," Hill said.
"This is a massive achievement for me. I think it means a lot more to other people who’ve been involved in this process because it’s not just three years, it’s not just four years, it’s 12 years of hard work.
"I’m happy with how I put the race together. Tonight, my PB puts me sixth So I’ve got to go out there exactly the same as this morning and hopefully there’s a bit more in there.
Ahead of a big night in the pool for Irish swimmers, Hill said it shows that "the girls know how to do it".
She will be competing in the 100m backstroke tonight and Mona McSharry (100m breaststroke) and Ellen Walshe (400m individual medley) will also be swimming in their respective finals.
Hill added: "I’m itching to get back here so we can watch Wiffen as well.
"We did talk about coming in that this was the most competitive Irish swimming group that we’ve brought and we’re starting to prove ourselves a little bit."
