Vincenzo Nibali attacked on the rain soaked Mortirolo climb to move into second overall but says that it is going to be difficult to dislodge Movistar's Richard Carapaz in the Giro d'Italia lead.
Nibali (Bahrain-Merida) gained 1-22 minutes on his rival Primož Roglič (Jumbo-Visma) to move up from third to second overall when he went free in a move with Carapaz.
"I'm happy," said Nibali, who could dry off and warm up while waiting for an anti-doping test.
"I knew there would be rain and I had a rain jacket because I knew the descent would be very cold. What we tried to do, going on the attack, was certainly a good thing because we succeeded in gaining time on Roglič.
"Now for the GC, we need to take a look and think about something to beat Carapaz. It's not easy because he's shown himself to be very strong, in-form and ready for this Giro d'Italia."
Carapaz moved into the lead on the stage to Courmayeur, becoming the first rider from Ecuador to wear the prized pink jersey. He is also posed to become the first Ecuadorian to win the race if Nibali and others do not mount a sufficient charge.
He leads with 1-47 minutes on Nibali and 2-09 minutes on Roglič.
Nibali launched his offensive on the Mortirolo with 35km to race, while ahead an escape with eventual winner Giulio Ciccone (Trek-Segafredo) rode free. Roglič and Simon Yates (Mitchelton-Scott) both lost ground.
"We did a good attack and a few GC contenders lost contact," Nibali added. "Carapaz showed that he's in form. Today he managed the situation very well but I don't know, it didn't seem to me that he was at his best. But having a Landa riding like that meant that he was able to manage the situation."
Landa joined Carapaz and Antonio Pedrero helped for some time. Then, Carapaz had Andrey Amador drop back from the early escape. Nibali faces not only a "solid" Carapaz with 1-47 but an equally strong Movistar squad.
"In this moment, it's really complicated," Nibali added. "He's shown himself to be very solid."
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