IMO the format for the year-end championships needs to be changed. They should just make it double elimination during the group stage. I'll use Group A as an example: Match 1 #1 Fed beat #7
Verdasco and #4 Murray beat #5 Del Potro Match 2 #1 Fed beat #4 Murray and #5 Del Potro beat #7 Verdasco Fed qualifies for semis, Verdasco eliminated. Del Potro and Murray would then play again for ...