Rafa Nadal urged tournament organisers to make more consistent surfaces for hard court events after easing past American Taylor Dent 6-2, 7-5 to make the third round of the Cincinnati Masters on Wednesday.
Andy Roddick needed three sets to beat 46th-ranked Ukrainian Sergiy Stakhovsky 6-4, 6-7, 6-1, while fellow American Taylor Dent upset Feliciano Lopez to advance to the second round of the Cincinnati Masters on Monday.
The world number three was upset 7-6, 6-3 by American Taylor Dent in the Australian hardcourt championship.
Robby Ginepri triumphed 4-6, 6-0, 3-0 after fellow American Taylor Dent quit with heat exhaustion in the third set.
Andre Agassi beat Spain's Tommy Robredo while Marat Safin knocked out Peruvian Luis Horna at the Madrid Masters.
Novak Djokovic outclassed Finland's Jarkko Nieminen 6-4, 6-2, 6-3 to move safely into the Wimbledon third round on Wednesday.
Second seed Garbine Muguruza, bidding to add the Wimbledon crown to her French Open title, was sensationally beaten in the second round on Thursday by Slovakian qualifier Jana Cepelova 6-3, 6-2 in the shock of the tournament so far.