Winning machine Novak Djokovic brushed aside Juan Martin del Potro while Andy Murray overcame an ankle injury as they joined champion Rafa Nadal in the French Open fourth round on Saturday.Twice runner-up Robin Soderling also crushed Leonardo Mayer 6-1 6-4 6-3 and Maria Sharapova overcame Chan Yung-jan 6-2 6-3 in bright but blustery conditions in a wide open women's draw.