David Ferrer's 12-0 record versus Nicolas Almagro may have kept Almagro from having his finest day. Almagro was two points from his first Slam semifinal at the Australian Open. Three times Almagro served for the match in the third and fourth sets, and three times Ferrer broke Almagro. Eventually Ferrer won by two breaks in the fifth set.
Is Ferrer Almagro's worst nightmare? Ferrer now is 13-0 versus his fellow Spaniard, and I think that dominance kept Almagro from his first semifinal in a Slam.
Ferrer Defeats Almagro in Grueling Five-Set Match to make Aussie Open Semis (Australianopen.org)
Just imagine for a moment that you played tennis against someone often, but when you played a match when it mattered they always beat you. Then, at the most important tournament of your life you played them again and you were beating them. How good would it feel? But, the specter of never beating the person reveals itself as you are about to close them out. How emotional would you be? How hard would it be to focus on just hitting the ball?