Sir Bradley Wiggins' Tour de France hopes took another blow after injury and illness forced him to withdraw from the Tour de Suisse.
The 34-year-old suffered bruising and swelling to his right thigh in a crash during Tuesday's stage four, to add to a chest infection, and withdrew on Wednesday morning.
The former Tour de France winner has returned to the United Kingdom in a bid to race in the British National Time Trial Championships in Monmouthshire on June 26.
The three-time Olympic gold winner had expected to miss out on selection for the Tour even before these setbacks, with Chris Froome to lead Team Sky's bid.
"Ironically, I was the last man in the peloton, trying to stay out of trouble when it happened," Wiggins told Team Sky's official website.
"They all slammed on the brakes ahead of me but there was another rider riding full gas who rode straight into the back of me.
"I've got quite a lot of swelling on the left-hand side of my right knee.
"It's one of those things, I've been pretty fortunate this year with crashes.
"I probably could have started today but it's best to play it safe and come home now.
"I really want to try to be ready for the Nationals next Thursday so I didn't want to jeopardise that for the sake of pushing on and potentially doing more damage.
"The plan is to get home today, have 24 hours off the bike and then I'll be good to go again and finalise my preparations for Wales next week."
Team Sky's doctor Steve Baynes said Wiggins was best served returning to the UK for treatment.
"Alongside the team's physio, Nathan Thomas, I assessed Bradley last night, and again this morning," said Baynes.
"He's suffered some pretty bad bruising on the left side of his right thigh muscle which is restricting his movement on the bike and obviously causing him discomfort.
"That's going to require some treatment so, having spoken to Brad, we felt the best plan of action would be to withdraw him from the race and fly him back to the UK."
Italian Sacha Modolo claimed victory on stage five from Ossingen to Buren an der Aare, with Mark Cavendish embroiled in a crash that put paid to his chances on the day.
Cavendish suffered no serious injury and continued to complete the stage, but lost too much time to trouble the pace-setters.
His Omega Pharma Quick-Step team-mate Modolo held off Cannondale's Peter Sagan and German John Degenkolb to secure victory.
Germany's Tony Martin retained the overall lead, with Dutchman Tom Dumoulin second and Sagan third.