Josh Griffiths arrived on the Tube, went off with the fun runners and stunned himself as he became the top British finisher at the Virgin Money London Marathon.
The 23-year old Swansea Harrier was running the 26 mile distance for the first-time and thought he might have an outside chance of making the Welsh team for next year’s Commonwealth Games.
Instead he clocked two hours, 14 minutes and 52 seconds for a stunning 13th place finish, securing the selection criteria for this summer’s IAAF World Championships in London.
Robbie Simpson finished just behind to take the other qualifying slot while Alyson Dixon and Charlotte Purdue were the first two home runners to finish the women’s race.
"I'm still a bit in shock, I still can't quite believe it," said Griffiths, who warmed up for the race by winning a half marathon in Llanelli and his local Park Run.
"I never even considered making the World Championship team and right now everything is just a bit of a blur but it proves that hard work can pay off.
"I started pretty steady because this was my first marathon but I felt stronger and stronger as the race went on. I still knew it would be a big ask but I thought 'why not give it a go' and the crowd really drove me on.
"I was in good shape, but given that was my first attempt at the full distance, it couldn’t have gone much better.
"It's just hard to explain quite how I'm feeling, I've certainly got to rethink my plans for the next few months now. I got no special treatment, I took the Tube to the start like everyone else!”
Dixon proved the value of hard work as she defended her British marathon title, finishing 15th in the women's race in a personal best time of two hours, 29 minutes and six seconds.
The 38-year old has been averaging 100 miles a week in training, with recent altitude trips to Kenya and France her big race preparation.
Purdue, 25, came just behind, also in a new best time, but there was disappointment for five-time Olympian Jo Pavey. Running in only her second marathon, she dropped out after 16 miles.
"I came here looking to finish top Brit and get that personal best and qualifying time and it feels amazing to achieve it," said Dixon, who finished 28th in the Olympic marathon in Rio last year.
"Everything in training has been aimed at this race and it feels great to have achieved my goals. Preparations have been going really well but this was a tough selection race. I just decided to give it everything, if I blew up then I didn’t care, I wanted to push it to the maximum."
Kenya's Mary Keitany set a new women’s only race world record while Daniel Wanjiru took victory in the men's race.
Keitany broke Paula Radcliffe's 12-year women's only marathon record after posting two hours, 17 minutes and one second while London newcomer Wanjiru clocked two hours, five minutes and 48 seconds.
"This means so much, it’s the greatest win of my career," said Keitany, a London winner in 2011 and 2012. "It was a great day for me, everything went right and I'm so proud of that time."
Wanjiru is now looking to this summer’s World Championship marathon and admits he has got the taste for even quicker times.
"At the beginning the race was very fast, inside world record pace. As the race was very fast anything can happen. I have tasted world record pace which was good for me," he said.
Team GB’s Olympic rowing pair champions Helen Glover and Heather Stanning went from team-mates and best mates to rivals as they got 35,000 athletes on their way and then pulled on their trainers to tackle the race.
Glover crossed the line in a remarkable three hours, five minutes and 25 seconds - good enough for 114th place - while Stanning finished just 27 minutes later.