Novak Djokovic set up a potential third-round meeting with Britain's Kyle Edmund at Wimbledon with a clinical 6-1 6-2 6-3 victory over Horacio Zeballos.
The three-time champion is joined in the next round by world number one Rafael Nadal, who was made to work in a 6-4 6-3 6-4 win over Mikhail Kukushkin.
British number one Edmund is playing American Bradley Klahn.
Djokovic needed lengthy treatment on his left thigh at the end of the seventh game in the third set.
That was his only real problem against world number 126 Zeballos, who was appearing in the Wimbledon second round for the first time.