Italy’s Vincenzo Nibali crosses the finish line to win the thirteenth stage of the Tour de France. (Source: AP)

Stamping his dominance in the mountains and on the race overall, Italy’s Vincenzo Nibali has won the 13th stage of the Tour de France as the race entered the Alps and went up the hardest climb so far this year.

The Italian race leader collected his third Tour stage win this year on Friday by beating two other breakaway riders at the end of the grueling 197.5-kilometer (122-mile) trek from Saint-Etienne to Chamrousse ski station.

The first of two days in the Alps lived up to its billing as the daunting final ascent of 18 kilometers (12 miles) with a 7.3 percent gradient shook up the overall standings.

The main casualty was Australia’s Richie Porte. The Sky Team rider began second to Nibali overall, but lost time in the climb.