Richie Porte has admitted that his inability to deal with the hot conditions on Friday was the key factor in a disappointing stage 13 for Team Sky.

The Australian begin the day second in the overall standings behind Vincenzo Nibali, who managed to record another stage victory, but his struggles saw him fall over 11 minutes behind his rival on his way to the summit finish at Chamrousse.

"I don't think I dealt with the heat very well," Porte told reporters. "It's one of those things. It's a massive shame, but we will see what happens tomorrow.

"I feel more for my teammates, who have been brilliant for me every day. If it happens to me, it can happen to other guys too. We will just keep on pushing."

Porte, who became Team Sky's race leader after injury forced Chris Froome to pull out, is now 16th in the standings.