Novak Djokovic breezed into the third round with a 6-2 6-1 victory over Martin Klizan yesterday but Ivo Karlovic made sure Rafael Nadal had to work a lot harder.
Nadal eventually won through 7-5 6-7(4) 7-6(4) after two hours and 43 minutes of a closely-fought encounter.
There was no such drama for Djokovic as the world number one dropped only three games against Klizan.
Djokovic converted half of the 10 break points that came his way to sweep aside his error-prone Slovak opponent. French Open champion Stan Wawrinka also maintained his winning run with a 7-6(3) 6-3 victory over Viktor Troicki to set up a third-round contest with Marin Cilic.
Third seed Andy Murray beat American Steve Johnson 6-2 6-4, Bernard Tomic eliminated seventh seed David Ferrer 6-4 6-2 and Japan's Kei Nishikori overcame Australian Nick Kyrgios 1-6 6-4 6-4.