L'Alpe d'Huez - Former champion Vincenzo Nibali was doubtful for the remainder of the Tour de France after a collision on Alpe d'Huez Thursday left him nursing a sore back.
Nibali, who claimed his sole yellow jersey in 2014, was riding ahead of eventual stage winner Geraint Thomas when he came crashing down four kilometres before the summit of the race's legendary climb.
The Bahrain team rider was helped back on his bike and, with a courageous effort, rejoined the chase of a small group of stage leaders in a thrilling finale that saw Thomas triumph for the second alpine stage in succession.
He eventually finished in seventh place, only 13secs behind race leader Thomas, who took his overall lead over four-time champion and teammate Chris Froome to 1min 39secs.
Nibali is fourth overall at 2:37 behind Thomas, but said: "I've got a very sore back, I don't feel that great.
"I was struggling to breathe at one point from the pain, so we'll have to see if my osteopath can do something for me."
Thomas said: "I was on his (Nibali) wheel, but I didn't see if he hit a spectator. I rode over his back wheel and managed to get back on. It's not good to see, because he should have been there challenging for the stage.
"But it's just fortunate that we were ok."
The profile of Friday's 13th stage could help the Italian, a former two-time winner of the Giro d'Italia, if he decides to continue.
It is mainly undulating 169.5 km race from Bourg d'Oisans to Valence.