La Toussuire - Race leader Chris Froome hit out at defending Tour de France champion Vincenzo Nibali for launching his stage-winning attack just when the Briton suffered a mechanical problem on Friday.
The incident was reminiscent of that on the 2010 Tour when Alberto Contador attacked Andy Schleck as the Luxembourg rider, then wearing the yellow jersey, had problems with his chain.
The Spaniard then went on to win the race although he was later stripped of the title following a positive dope test with Schleck promoted from second to take the honours.
"It's pretty self explanatory really, going up to the col de la Croix de Fer I had a mechanical problem," said Froome after the 19th stage.
"A piece of asphalt got stuck between my brakes and my rear wheel and the rear wheel just jammed up. I had to stop and get it out before I could continue.
"It seems to me that Nibali had the whole climb to attack but he chose the moment I had a mechanical to make his move and I've heard from other riders that he turned and attacked. In my opinion it's very unsportsmanlike.
"It's not in the spirit of the Tour de France."
Nibali, not a threat to the yellow jersey after dropping out of contention in the first block of racing, went on to win the stage ahead of Colombian Nairo Quintana and Froome, who were second and third respectively.
Some riders believe the wearer of the yellow jersey should not be attacked if he suffers a mechanical problem or a crash.
Nibali, however, said he did not see the incident.
"I had turned around to talk to my team mate Tanel Kangert," said the Italian, who is now fourth overall 6:44 off the pace.
Froome went to confront Nibali after the finish.
Asked what he was told by the Briton, Nibali replied: "It can't be repeated."
Froome said: "I told him what I thought of him."