The 27-year-old underwent knee surgery last month but is confident he will be able to feature in the clash at the Maracana
The Juventus star underwent minor knee surgery last month and was only able to play an hour of Chile's 3-1 win over Australia in their opening Group B game last Friday.
Victory over Spain in Rio de Janeiro on Wednesday could seal qualification for the last 16 and Vidal has indicated that he should to be available.
"I'll try to be 100 per cent," he said. "Physically I think I am fit. I feel good and I've tried very carefully in training.
"My knee has responded very well.
"Playing against Australia was my decision. As I said, I wanted to play at the World Cup even if it meant risking my knee."
Vidal went on to say that Spain will provide a stern test at the Maracana, dismissing any notion that the reigning world champions are past their best and suggesting that they are actually better than they were four years ago.
"We'll have to be very strong," the 27-year-old continued.
"Are they burnt out? I don't think so. Spain have increased in quality and have more technical players.
"If you stop to look at this Spain and the one in South Africa, I believe this is stronger. We'd take a draw, but we'll go out to win as always."