Rafael Nadal has revealed concerns about a blister on his racquet hand ahead of his Australian Open semi-final meeting with Roger Federer.

The Spaniard explained that the ailment is not impacting on his forehand, but admitted that having his palm taped up is affecting his serve.

"With the forehand, it's not a big issue," BBC Sport quotes him as saying. "With the serve, a little bit. I feel that with the tape I can lose the racquet when I'm serving. That's my feeling - the racquet can go.

"That's a terrible feeling for a serve, because then when you have this feeling you are not able to accelerate at the right moment. You lose a little bit the coordination. That's a big deal."

Nadal has not lost to Federer at a major since the Swiss defeated him in the 2007 Wimbledon final, and holds an overall 22-10 lead over him in their head-to-head.