Fed is not going to beat Nadal if they make the semifinal. Roger is sick...he was throwing up after his first match. Commentators were saying Roger was still sufferring from the flu yesterday, but as a fighter he'll continue to play. Roger shouldn't even be playing, he should withdraw just like Davydenko did. There's no need to put himself in this situation.
Other reason the court is slow which suit perfectly for Nadal, who's healthy(didn't get the virus).
Federer > Davydenko > Nadal > Federer