Astana's Vincenzo Nibali tightened his grip on the Tour de France's general classification with a solo victory on Stage 13 of the race.

The Italian national champion, enjoying his second spell in the yellow jersey having lost it briefly to Tony Gallopin (Lotto-Belisol) earlier in the race, attacked with 3.5 kilometres left to take his third stage win of the race.

The win came despite an almost-major setback for the Kazakh team, after Nibali's chief lieutenant Jakob Fuglsang crashed earlier in the stage. The Dane raced on, but finished the stage sporting some impressive cuts and road rash after his front wheel slipped from underneath him on a bend.

On the final 18.2 kilometre climb of Chamrousse, Nibali found himself in a group of general classification contenders chasing down the day's breakaway, which consisted of Leopold König (NetApp-Endura) and Rafal Majka (Tinkoff-Saxo).

After catching the two leaders with just over six kilometres remaining, Nibali worked with them until the final stages, where he attacked.

The 2013 Giro winner held off the duo to take the win on top of the hors-categorie climb, with Majka and König finishing second and third respectively.

“It’s a special day today. I’m very happy,” Nibali said.

“I just wanted to gain some time, as much time as I could. I knew [Alejandro] Valverde and [Richie] Porte were close to me.

"In the end there was only Valverde and me. In the end I just felt stronger than Valverde.

"It was a hot day. It felt like I was in Palermo or Messina, my hometown.”

Porte was the day's biggest loser, dropping from second to sixteenth overall having lost over eight minutes to Nibali on the day. The Australian is now 11'11" down overall, and Sky's streak as the Tour's winning team looks almost certain to have reached its end.

Sky's directeur sportif Nicolas Portal said: “He had a bad day. He didn’t react well with the heat." 

“He said he felt like he was going to be sick. You can’t really do much.

"He just felt really empty. We’ll have some happier days. We’re not going to give up like that.”

Saturday's Stage 14 features a 177 kilometre route from Grenoble to Risoul, and features three major climbs.