Complex sentence: He had in his strongest form in the beginning of the 1960s with few superiors on clay, defeating players such as Manuel Santana, Nicola Pietrangeli, Fred Stolle, Roy Emerson and Neale Fraser.
Split into simpler sentences: He had in his strongest form in the beginning of the 1960s with few superiors on clay. He defeated many of the contemporary highest ranked players like Manuel Santana, Nicola Pietrangeli, Fred Stolle, Roy Emerson and Neale Fraser.