(Adds details) By Julien Pretot LA TOUSSUIRE, France, July 24 (Reuters) - Defending champion Vincenzo Nibali enjoyed some rare success in this year's Tour de France by claiming a vintage win on the 19th stage as Chris Froome came under fire but retained the overall lead on Friday. Nibali, who had dropped out of contention in the race after a tough first week and a bad first day in the Pyrenees, broke away from a group of top riders 61 kilometres from the finish. ... More...