Federer seems to be taking alot of pace off his first serve in favor of direction and angle. The upside is a higher first serve percentage and greater disguise with the ability to pull people wide off the court for an easy put away. The downside is no aces. Davydenko seemed to catch on a bit in the second set of the Doha final but Fed switched gears and started hitting flat ones again for a game to keep him honest. Oddly enough, although Federer hardly hits aces anymore, his serve has been pretty much unbreakable. Its been very effective against good reflex returners like Denko who can get anything back in and force a neutral rally even off good serves since the wide serve opens up the court for an easy put away even if they can get the ball back well. It will be interesting to see how this plays out when and if he meets Nadal who, like Davydenko, can take a 13 mph serve and send it back deep for a neutral rally.