Geraint Thomas began his 2020 campaign at the Volta ao Algarve as Fabio Jakobsen claimed the opening stage win for Deceuninck-QuickStep in Portugal.
Thomas made his first racing appearance of the season for Team Ineos.
The Welshman has won the race twice but will act as support this year for the likes of Rohan Dennis, Michal Kwiatkowski and Dylan van Baarle.
Thursday's 183km second stage is from Sagres to Alto di Foia, with the first uphill finish of the race.
"I felt okay," said Thomas.
"The first race of the season is always a shock to the system with the intensity towards the end after being steady all day.
"It is good to be back racing and I am looking forward to the next four days.
"I would not expect myself to get a result here but I will work hard for the team and I should be good enough to do a decent job for them."