Ireland's Patrick Monahan finished in 16th place in the T54 men's marathon at the Paralympic Games in Rio.
Switzerland's Marcel Hug took the gold medal in the event with the silver going to Kurt Fearnley of Australia and Gye Dai Kim of Korea taking the bronze.
"It was the toughest race I've ever done," Monahan said afterwards. "If it wasn't my first Paralympics I would have dropped out after a lap it was that tough.
"I was sick last week, I was in bed for four days. I haven't done a lot of training in the last couple of weeks. I should be fresh but I think it was just the heat.
"There was a lot of people supporting me. I couldn't drop out."
Monahan was the last Irish athlete in action on the final day of the 2016 games and impressed in grueling conditions as temperatures got up to 28c at Copacabana.
The Kildare man, who was in action at his first ever Paralympics after being inspired to begin competing when he watched the London 2012 games, did not get off to the greatest of starts and was down in 23rd at the 5km mark.
However as other athletes wilted in the heat and dropped out, Monahan pushed on and was up to 18th at the 10k point and continued to push and rose up to 16th place where he would eventually finish.
Monahan completed the exhausting circuit in a time of 1:40:26 and saw off the late challenge of Switzerland's Heinz Frei, who was just three seconds behind him in 17th.