Richie Porte, who had announced that he was running his last Giro, was dropped from the first of the climbs on the program for this 19th stage between Marano Lagunare and the Castelmonte sanctuary, near Cividale (Friuli, north-east).
The Australian retired moments later, the pink race organization announced.
In the standings, Carapaz is 3 seconds ahead of Australian Jay Hindley before the last two days in the mountains and the final time trial on Sunday in Verona.
Richie Porte, 37, revealed himself in the 2010 Giro where he took 7th place. He finished third in the 2020 Tour de France.
