Not taking anything away from the brilliant performance by Del Potro who fully deserves the USO title by beating both No.2 and No.1 convincingly. (Wonder how Andy Murray must feel now?) Which was the worst performance by Federer in a slam final-Wimby 08, AO 09 or USO 09? USO 09 and AO 09 were very similar in many ways. Hampered by the low first serve percentage, had many chances in a couple of sets to close out the match early and of course the complete collapse in final set losing it 2-6 in both occasions. And no, we are not comparing any French Open finals in this thread. Out of the three: Wimby 08, AO 09 or USO 09, which one?