Spaniard Juan Ayuso blitzed the 18.5km individual time-trial on stage three of the Tour of Romandie on Friday to take the overall lead of the race.
The 20-year-old is a teammate of two-time Tour de France champion Tadej Pogacar at Team UAE and rode to a landmark third at the Vuelta a Espana last season.
However, this year he has been dogged by tendonitis in his heel.
Normally a strong climber, Ayuso was modest in his ambition to defend his lead on Saturday's stage over five Alpine climbs on the way to the ski resort of Thyon at an altitude of 2 076m.
"On short efforts like today I can perform at my best, but tomorrow in the mountains will be more representative of my form," said Ayuso after just his third competitive day in the saddle of 2023.
"If I can't win I'll go all in for Adam (Yates). I'll try and defend the yellow jersey, it's a very good opportunity for the team."
To claim his first World Tour triumph Friday, Ayuso completed the largely flat time-trial in 25min 15sec in a rural setting in the French-speaking part of Switzerland, with less cornering than an urban route, and less road furniture.
American Matteo Jorgenson of Movistar was second at five seconds while Ayuso's British teammate Yates was third at 17sec.
Ayuso leads the overall standings by 18sec form Jorgenson with world time-trial champion Tobias Foss, a Norwegian who rides for Jumbo-Visma, in third at 19sec.
French climber Romain Bardet had a disappointing day, dropping 57sec on the winner, while 2019 Tour de France winner Egan Bernal dropped 59sec as he struggles for full fitness.
Foss and prologue winner Josef Cerny set the early pace with Foss ending 25sec down in eighth.
Chris Froome, a four-time Tour de France winner, finished 3min 19sec down as he seeks a start place on the Israel Premier Tech team for the Tour this year.
After Saturday's likely decisive stage, Sunday's finale is a 170km run to Geneva over two categorised climbs.