Magheralin's Daniel Wiffen has broken the Irish national record in the men's 800m freestyle at the Olympics, finishing in a time of 7:51.65.
However, despite winning his heat, Daniel has missed out on a place in the final, finishing 14th overall following the heats.
The top eight finishers overall qualify for the final.
Starting in lane 8, the 20-year-old was in seventh a quarter of the way through the heat, but by the halfway point he had moved into the top three.
In the final 50m he had a strong finish, powering his way into the lead to finish 0.42 seconds ahead of Venezuela's Alfonso Mestre.
Speaking after the heat, a beaming Daniel said, “I am ecstatic! I got a Personal Best on the big stage. I came out top of the race.
"It is the Olympics, and I am happy to be here. I rebroke my old Irish Senior Record which is incredible. I have dropped about 20 seconds this year on it which is a lot.
"I felt it was like a 1v1 race at the end and I thought I have got to win this. I have got to show the nation what I am capable of.
"I have huge support coming from home, my parents, family and extended family. It is my mum’s birthday today so happy birthday, mum!”
There is some good news for Wiffen, though - he has moved himself up 10 places on pre-meet rankings.
Daniel, who also holds the Irish record in the 1,500m freestyle, will be back in action in that event on Friday.