Defending champion Sir Bradley Wiggins has withdrawn from the Tour de France after a chest infection and a knee injury left him unable to train.
Wiggins had already been told by Team Sky that he would be riding in support of team-mate Chris Froome, but the absence of last year's yellow jersey winner still represents a huge blow for all concerned.
Wiggins, whose fitness issues saw him withdraw from the Giro d'Italia earlier this month, said: "It's a huge disappointment not to make the Tour.
"I desperately wanted be there, for the team and for all the fans along the way - but it's not going to happen.
"I can't train the way I need to train and I'm not going to be ready. Once you accept that, it's almost a relief not having to worry about the injury and the race against time."
After the unforgettable events of 2012, which saw Wiggins become the first Briton to win the Tour before going on to win time trial gold at the London Olympics, 2013 is becoming memorable for all the wrong reasons.
First he found out Team Sky had nominated Froome as their lead rider and he would effectively not be defending his title, then he endured a troubled time at the Giro d'Italia, culminating with his injury-enforced withdrawal.
He has not been able to train fully since then.
Team Sky principal Sir Dave Brailsford said: "With illness, injury and treatment Brad has gone past the point where he can be ready for the Tour. It's a big loss but, given these circumstances, we won't consider him for selection."
"He hasn't been able to train hard since the Giro and now he needs further rest. Whilst we all know these things happen in sport, it doesn't take away from the fact that this is a huge disappointment for everyone in the team - and above all for Brad.
"It's incredibly sad to have the reigning champion at Team Sky but not lining up at the Tour. But he's a champion, a formidable athlete and will come back winning as he has before."
Wiggins, who crashed out of the 2011 Tour when breaking his collarbone in a crash, refused to be downbeat - either for himself or the team.
He added: "I've been through this before, when I broke my collarbone, so I know how it works. I'll get this sorted, set new goals for this season and focus on those.
"This team has so many riders in great shape, ready for selection and we set incredible standards for performance which shouldn't be compromised. We need to have the best chance to win."
Team Sky doctor Richard Freeman gave the formal verdict on Wiggins, ordering no activity for the next five days before a gradual return.
With the tour beginning on June 29, that left Wiggins with no chance of participating.
Freeman said: "The chest infection that caused his withdrawal from the Giro has responded to treatment and rest. It has completely cleared up.
"However, further medical investigations on the knee injury that we were managing at the Giro showed the condition was more significant than we thought.
"It's needed intensive treatment and, whilst it will be fully resolved, Bradley now needs to rest completely for five days before a gradual, return to full training over a period of two to three weeks."
Team Sky are believed to be lining up Richie Porte to take Wiggins' place as chief support to Froome.
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