Budapest - Ben Proud won the men's 50m butterfly gold at the world aquatic championships on Monday - but only realised he had won when no-one else celebrated.
Proud, 22, clocked 22.75 seconds in the sprint event with Brazil's Nicholas Santos second at 0.04 secs back while Andrii Govorov of Ukraine took bronze at 0.09 in a tight finish.
"At first I didn't realise I had won," admitted Britain's Proud, clearly shocked by his own victory.
"I was waiting for someone else to start celebrating, but when no one did, I looked on the scoreboard and saw my name on top."
Proud was born in London, but moved back to the UK from Kuala Lumpur, Malaysia as an 11-year-old to follow his dreams of becoming a pro swimmer.
"It's a weird feeling, this is something I've dreamt of since I started swimming," he said.
"It's the reason I moved to the UK.
"For it to happen today is amazing, I was never going to give up on that dream, I was going to keep going into my mid-30s."
Proud qualified as the fourth fastest from the semi-finals and the 2014 Commonwealth champion was an outsider for gold in Budapest.
"After last night I might not have looked in pole position, but deep down I knew if I got the start right, I'm in with a shout for the gold medal," he said.
"The past 24 hours have really been a mental battle getting my head in the right place, so I can race not even thinking about medals.
"It's really all about that first 15m, I just let my body takeover and switch my mind off.
"It took me a while to realise I'd won, I was shocked at first, it's a dream come true."