Simon Yates relinquished the Vuelta a Espana lead to Jesus Herrada on Thursday as the day's breakaway dominated stage 12, allowing Alexandre Geniez to take the victory.
Yates had managed to cling onto his one-second lead 24 hours earlier but the size of the gap to an 18-man attack left the Mitchelton-Scott rider in the dust this time.
While the majority of those out in front, setting a relentless pace, were not of genuine concern to Yates, Herrada took his opportunity.
Starting the day in 22nd, five minutes and 45 seconds back, the Spaniard could not go the distance with AG2R-La Mondiale man Geniez but did enough to maintain a strong finish comfortably ahead of Yates and the peloton.
As Herrada splintered away to finish just over two and a half minutes back on the leaders, Geniez kickstarted a sprint and had the legs to tear away from Dylan van Baarle and Mark Padun.
Geniez then clashed with an individual running beyond the finish line, causing a collision with Van Baarle that appeared to have the Team Sky man in some pain.
That incident could not take the shine of Geniez's achievement, though, with Herrada likewise able to celebrate as Yates and Co finished 11 minutes and 39 minutes back.
A delicate lead is no more for Yates and he and the chasing pack now have work to do to make up a significant deficit.
COFIDIS OUT IN FRONT
With no movement in the race for the other jerseys, the focus was on Vuelta debutant Herrada as the Cofidis rider stepped into the red jersey.
The Spaniard leads Yates by three minutes and 22 seconds, with Alejandro Valverde remaining a second further back and Movistar team-mate Nairo Quintana still in contention.
It is turning into a brilliant Vuelta for Cofidis having already seen Nacer Bouhanni claim a stage win, while Luis Angel Mate continues to lead the way in the King of the Mountains.
"I'm very, very happy," said Herrada. "It's a nice present for me and the whole team. We'll try to keep the jersey for as long as possible."
1. Alexandre Geniez (AG2R-La Mondiale) 4:22.59
2. Dylan van Baarle (Team Sky)
3. Mark Padun (Bahrain-Merida)
4. Dylan Teuns (BMC Racing)
5. Victor Campenaerts (Lotto Soudal) +0.02
1. Jesus Herrada (Cofidis) 50:28.56
2. Simon Yates (Mitchelton-Scott) +3.22s
3. Alejandro Valverde (Movistar) +3.23s
1. Alejandro Valverde (Movistar) 85 points
2. Peter Sagan (Bora-Hansgrohe) 83 points
3. Elia Viviani (Quick-Step Floors) 66 points
King of the Mountains
1. Luis Angel Mate (Cofidis) 60 points
2. Benjamin King (Dimension Data) 33 points
3. Bauke Mollema (Trek-Segafredo) 30 points
The first of three successive days in the mountains sees a 175km ride from Candas to La Camperona on Friday, concluding with a brutal ascent to the finish.