Photo: DavisCup.com Croatian tennis players Marin Čilić and Ivo Karlović teamed up in doubles play to take on Argentina's David Nalbandian and Eduardo Schwank Saturday afternoon in Buenos Aires in the Davis Cup quarterfinal round. With world #10 Juan Martin del Potro defeating Karlović in straight sets on Friday in singles play and Čilić edging out Nalbandian 6-3 in the … [Read more...] about Čilić, Karlović go the distance in Buenos Aires