London Marathon praised Matthew Rees for helping to a fellow athlete to complete the final stretch of the race.
Matthew Rees put his arm around David Wyeth whose “legs just crumbled” at the last bend – about 200 metres from the finish line.
Helped by a marshal, Mr Rees proceeded to walk Mr Wyeth towards the finish line as they were applauded to the end of 26.2-mile course by the crowd that included Princes William and Harry.
Finishing with a respectable time of 2 Hours 52 minutes and 26 seconds, the pair then separated and Mr Wyeth, who was said to be running in memory of his uncle, was taken away for medical treatment.
Mr Rees has been praised for encompassing the spirit of the marathon.
The 29-year-old said helping his fellow competitor was “more important” to him than his race time.
The bank worker, a member of the Swansea Harriers running club, said: “I took the final corner thinking ‘right, it’s nearly done, time to sprint’, and I saw this guy and his legs just crumbled below him.
“I saw him try to stand up again and his legs just went down again, and I thought ‘this is more important, getting him across the line is more important than shaving a few seconds off my time’.
“I went over to try and help him and every time he tried to get up he just fell down again and again, so I just tried to cheer him on, picked him up and said: ‘Come on, we can do this’.
“He was really grateful, but he wasn’t very coherent, he was just like ‘I have to finish, I have to finish’.
“And I said ‘you will finish, you will get there, come on let’s do this’, but every time he tried to move he would just fall again so it was important to guide him.”
Former marathon winner Baroness Tanni Grey-Thompson tweeted: “Matthew Rees refuses to give up helping David Wyeth across the line. Wow.”
London Marathon tweeted: “Matthew Rees, you’ve just encompassed everything that’s so special about the #LondonMarathon. We salute you.”