South Africa's Chad le Clos has admitted that he is "massively disappointed" to lose his title in the 200m butterfly at the World Championships in Kazan.
The 23-year-old had to settle for silver after Hungary's Laszlo Cseh stormed to victory in 1:53.48.
Despite failing to defend his title, Le Clos has vowed to come back stronger after clocking a time of 1:53.68.
"It's massively disappointing, but credit to Laszlo - he swam a great race, so I'm happy for him," Le Clos told Eurosport. "If I look at the times, I should have been a little bit faster, but that's sport for you. I ran out of fuel in the last 10m. I'll be training double hard to get back my gold."
Le Clos is the Olympic champion in this event.