The Juventus star underwent minor knee surgery at the end of the domestic season, and was only able to play an hour of Chile's 3-1 win over Australia in their opening Group B game last Friday.
Another victory over Spain in Rio de Janeiro on Wednesday would almost certainly be enough for Chile to reach the last 16 - and Vidal has offered coach Jorge Sampaoli a huge boost by indicating that he hopes to be available for the full match.
"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 and European champions are past their best despite their 5-1 mauling at the hands of the Netherlands in their opening fixture.
"We'll have to be very strong," the 27-year-old added.
"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."
