( CNN ) Both ATP and WTA players back in action this week at the Masters . Reigning men 's champ Rafael Nadal not competing because of an injury . Novak Djokovic aiming for first Cincinnati win after finishing runner up four times . Women 's singles champion Victoria Azarenka starts title defense on Tuesday .
Both ATP and WTA players back in action this week at the Masters . Reigning men 's champ Rafael Nadal not competing because of an injury . Novak Djokovic aiming for first Cincinnati win after finishing runner up four times . Women 's singles champion Victoria Azarenka starts title defense on Tuesday .