French hope Seixas storms Basque Tour time-trial opener
The six-day race embarked in bright sunshine from the landmark Guggenheim Museum in downtown Bilbao and will rack up 809km of hilly and mountainous terrain this week.
The 19-year-old Seixas was an early starter in the individual race against the clock, timing 17min 09sec with compatriot Kevin Vauquelin second at 23sec. Austrian rider Felix Grossschartner was third at 27sec.
"These seconds are precious, a win is already perfect but the gap is a bonus," said the emerging Seixas, who French cycling fans hope can end their wait for a Tour de France title one day.
Of the contenders for the overall title on this climb-filled tour, Red Bull riders Primoz Roglic (0:29) and Florian Lipowitz (0:33) are well placed.
Spain's Juan Ayuso of Lidl was 1min 26sec down, but Mexican Isaac del Toro and other climb specialists can fight back in the mountains as soon as Tuesday's stage two.
The contenders will set off from the famous bull-running town of Pamplona and head to the Mendukilo caves in the Picos mountains.