Japan's Naomi Osaka cruised into the third round of the Tokyo Olympics women's singles with a 65-minute victory over Viktorija Golubic.
Second seed Osaka, the favourite for the gold medal following Ashleigh Barty's first-round exit, beat the Swiss 6-3 6-2.
She will face Marketa Vondrousova, who beat Mihaela Buzarnescu 6-1 6-2, for a quarter-final spot.
World number one Novak Djokovic beat Bolivia's Hugo Dellien 6-2 6-2.
Serb Djokovic needed only 61 minutes to set up a second-round meeting with Germany's Jan-Lennard Struff.
Great Britain's Jamie Murray and Neal Skupski were knocked out of the men's doubles in the second round, losing 6-3 6-4 to Japan's Kei Nishikori and Ben McLachlan.