Germany's Tony Martin won a joint record fourth men's individual time trial world title at the Road Cycling World Championships in Qatar.
The 31-year-old completed the 40km route in 44 minutes 42.99 seconds, 45 seconds quicker than defending champion Vasil Kiryienka of Belarus.
Spain's Jonathan Castroviejo was third, with Ireland's Ryan Mullen, 22, taking an unexpected fifth.
It was Martin's second gold of the week in Doha.
His first, in the men's team time trial, was his last race for Etixx-Quick Step before he joins Katusha from 2017.
Switzerland's Fabian Cancellara, who is to retire this year and was not competing in Doha, won four titles between 2006 and 2010.
"I want to be world champion every year, so I am so proud I can ride in a world champion suit from next year," said Martin. "I've missed it a lot.
"The course was made for me. I just had fun on the road."
Mullen, who was born in Birkenhead, went to school in North Wales and has raced for Cannondale-Drapac since 2015, said he was "in disbelief" at his result.
"I saw all these big names come in a minute behind me and I was like 'did I take a short cut or something, have I missed a part of the course that everyone else has done?'" he said.
"If someone had said yesterday 'I'll give you 15th' I'd have snapped their hand off. Fifth is just completely unexpected."
Commonwealth time-trial champion Alex Dowsett was the best of two Britons competing, finishing 12th in 46 minutes 54.07 seconds. Compatriot Steve Cummings was 25th.
The women's elite road race takes place on Saturday, with Britain's Lizzie Deignan the defending champion.
The men's elite road race is on Sunday, with Britain's Mark Cavendish among the favourites.
2010 Commonwealth time trial champion David Millar on BBC TV:
"That was a phenomenal ride. Tony Martin at his very best.
"The course was flat, there are no surprises, it's just who can hold that power for the longest time. It was the display of a world champion. Nobody could ever have come close to matching that.
"Alex Dowsett will be disappointed in finishing 12th. I think he is capable of doing better. I'm not sure if it was the heat or the distance, because he's an hour record holder and we have seen him up there before.
"But I think it's only a matter of time before we see him up there again."