Mark Cavendish abandoned the Vuelta a Espana during the fourth stage on Tuesday.
The winner of the green jersey at the Tour de France, the HTC-Highroad sprinter was planning to use the Vuelta to help his preparations for the World Championships in Denmark next month for which he is one of the favourites.
But the Manxman struggled from the outset in Spain after getting detached in the opening team time trial and he had started stage four in 184th position, 16 minutes and 48 seconds adrift.
He was again well off the pace in the second half of Tuesday's 170.2 kilometres route from Baza, the first big test in the mountains at the final Grand Tour of the season which has taken place in searing temperatures.
Cavendish got off his bike approximately 40km from the mountain-top finish in Sierra Nevada and there will be plenty of interest now in his revised programme up to the Worlds in Copenhagen, which take place on September 25.
He would need permission from the Vuelta organisers and the sport's governing body the UCI to be able to ride other events during the Spanish Grand Tour.
The Manxman is the second HTC-Highroad rider to pull out of the Vuelta after his Australian team-mate Matt Goss abandoned the race during stage two.
Meanwhile Daniel Moreno (Katusha) went on to win the fourth stage - click here for full report.