Italian powerhouse Daniele Molmenti claimed gold in the men's K1 kayak canoe slalom final at Lee Valley.
Molmenti was more than a second ahead of silver medalist Vavrinec Hradilek, of the Czech Republic, with Germany's Hannes Aigner third.
Great Britain's Richard Hounslow went out in the semi-finals, failing to make the top 10 who challenged for a medal.
Olympic kayak: Richard Hounslow fails to make K1 final
"I'm very disappointed, it just feels like an opportunity missed. I'm gutted really," said the 30-year-old Briton.
"The nature of the sport is very unpredictable but the top guys keep performing.
"I am gutted that I couldn't put a performance that the crowd could be proud of.
"Anything can happen in the final, I could have got into the medals."
Hounslow will compete with David Florence, who failed to make the C1 final, in the canoe double semi-finals on Thursday.