Wiggins will begin his bid to become the first Briton to win the Giro this Saturday having achieved the same feat at last year's Tour de France before winning the Olympic time trial in London.
However he is placing Nibali, who won the general classification at the Vuelta in 2010, as the favourite ahead of the opening stage in Naples although that doesn't mean he isn't confident himself.
"I think he's the man to beat for me," said Wiggins. "This race is more suited to Nibali. It's his pride and joy. There's a lot at stake and he's the big Italian favourite.
"He's trained for it, he's in the best shape I've seen him in and he's got all the attributes needed for winning, like steep climbing and all those tricky things the Giro throws at you.
"He's got a good team and he's well prepared. I don't fear him but I respect him. I know his strengths and I know his weaknesses and, in that respect, I certainly won't underestimate him.
"That's what this year is all about. I've studied and watched him closely and he's difficult to read as he doesn't show a lot of emotion.
"I don't know if at this stage I will stay with Nibali on some of those real steep ones but I know I'm not going to lose a handful of time, maybe 20 seconds if I'm on a bad day.
"But I'm pretty confident I can stay with him, and I'm confident in the time trial I can take the time from him. I beat him in the Tour by six minutes 19 seconds, I only have to win the Giro by one second."
Team Sky rider Wiggins' last competitive outing was the Giro del Trentino, which was won by none other than Astana's Nibali with the Brit trailing home four places behind in fifth.
But Wiggins has no doubts that he will be able to tackle the uphill nature of this year's Giro and also maintain his ability to dominate the time trial.
"Most of the Giro is uphill this year so you have to train uphill," he said. "That's been the biggest difference between this and the Tour.
"You need to climb better on steeper climbs. I've rarely been on the time trial bike this year, just working improving on steeper climbs.
"There's been no compromise in my time trial. Fortunately, it's something I've done since I was a kid, I slot back onto the time trial quite easily.
"A lot of the work we do is threshold-based on climbs and I have a mountain time trial bike, which I train on. It hasn't affected the training, and the numbers are the same as last year."
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