Del Potro gradually improved against Federer at the Slams throughout 2009. After getting his backside handed to him at the AO, he took Fed to 5 sets at RG and narrowly lost. Then he took him to 5 sets at the US Open and narrowly won. Wawrinka's famous tattoo "Ever tried. Ever failed. No matter. Try again.Fail again. Fail better" surely couldn't have applied better than to Del Potro's efforts against Federer at the 2009 Slams!