Lukas Rosol produced one of the great upsets in recent memory. And he's not done yet.
If you enjoy superstars and drama, Day 1 at the World Tour Finals was a good place to be, thanks to Rafael Nadal and Roger Federer.
Slick hard courts. A raucous home crowd. No Rafael Nadal. Argentina has an opportunity to collar its maiden Davis Cup title in what will be the five most important points the country has ever played.