A 19-year-old Italian tourist was ambushed by a knife-wielding thug as she headed to a party on the Upper East Side - but she managed to disarm the attacker by grabbing his blade with her bare hands and wrestling it away, police said yesterday.

Carolina Ottone, 19, of Como, was at Lexington Avenue and 86th Street at about 11:30 p.m. Monday, when the brutal stranger approached her near a pharmacy.

He had been following her for about two blocks.

"He took his knife outside his pocket and grabbed me from behind," she told The Post.

Then the thug put his left arm around Ottone's throat. But he picked the wrong victim because the fiery Italian teen bravely fought back.

"The only thing I could do in that moment was to try to grab the knife and try to push him away," she said.