American Amber Neben won her second women's individual time trial world title with victory at the Road Cycling World Championships in Doha.
Neben, 41, won in 36 minutes 37.04 seconds, six seconds ahead of the Netherlands' Ellen van Dijk, with Australian Katrin Garfoot in third.
She is the second oldest women to win the event after France's Jeannie Longo, who triumphed in 2001 aged 42.
Britain's Hannah Barnes was 14th with compatriot Hayley Simmonds in 25th.
Simmonds won the British time trial title in 2015 and 2016 but admitted she struggled with the heat around the 28.9km course in Qatar.
"I truly believe I am capable of being up there in this event and I am just really, really upset that I am not showing that," the 28-year-old said.
"I felt really good in training but today I just felt hot and I just couldn't do the numbers.
"I wanted to do myself justice and prove selecting me was the right decision and I don't think I did that, which I am really upset about. I just hope I get another shot."
Barnes will return for Saturday's road race while Alex Dowsett and Steve Cummings race in the men's time trial on Wednesday.