Chris Froome finished seventh on stage two of the Ruta del Sol as Team Sky team-mate Wout Poels powered to victory.
Froome came in 27 seconds back as the four-time Tour de France winner competes for the first time since returning an adverse analytical finding for asthma drug salbutamol during his success at La Vuelta last year.
The under pressure English cyclist is still fighting to prove his innocence and before the event in Spain insisted he has "done nothing wrong".
On Thursday, it was Poels who took centre stage for Team Sky to beat Luis Leon Sanchez (Astana) and Tim Wellens (Lotto Soudal) to the line on the first summit finish of the five-stage race.
Froome, who won this event in 2015, admitted it is unlikely he will challenge for the Ruta del Sol crown.
He told Sky Sports: "I called it pretty early. I said to the guys, 'We need to get behind Wout here.' I'm not feeling my absolute best and obviously it's my first race.
"It's amazing. It's an amazing atmosphere, I mean the fans are great. I love racing out here.
"I think we have the leader's jersey as well so we will do absolutely everything we can to keep that leader's jersey on his shoulders."
When asked if distractions off the bike contributed to his decision, Froome responded: "Not at all. It's my first race so I wasn't coming here expecting to smash the whole race."
The action took place at the end of the 140-kilometre stage from Otura to La Guardia de Jaen.
Breakaway rider Diego Rubio (Burgos-BH) fought hard to remain in front but was eventually caught by a reduced peloton with 1.8km left of the Alto de Allanadas as Poels, Jakob Fuglsang, Tim Wellens, Mikel Landa and Luis Leon Sanchez set up an exciting finish.
Wellens broke clear inside the final kilometre but the Belgian faltered on the gruelling climb.
Poels and Sanchez fought for the line, with the 30-year-old Dutchman prevailing by two seconds to win the stage and take the lead in the general classification.
Third-placed Wellens crossed the line in the same time as Sanchez, with Movistar's Landa and Astana's Fuglsang two seconds further adrift.
Marc Soler (Movistar) was 17 seconds off the pace in sixth, with Froome a further 10 seconds back