Angelique Kerber (Getty Images)
Cape Town - Second seed Angelique Kerber is through to the last 16 of the women's tennis singles competition in Rio, along with former Wimbledon champion Petra Kvitova.
Kerber, the reigning Australian Open champion, ended the hopes of Canada's Eugenie Bouchard with a 6-4, 6-2 victory to set up a match with either Australia's Sam Stosur or Misaki Doi of Japan.
Also through to the last 16 was Kvitova, who beat another big name, Caroline Wozniacki, 6-2, 6-4.
She moves on to face either Ekaterina Makarova or Anna Karolína Schmiedlová.
Others to advance included American seventh seed Madison Keys, who saw off Kristina Mladenovic 7-5, 6-7 (4-7), 7-6 (7-5) after a hotly contested three-hour-and-16-minute battle.
Keys moved on to face Carla Suarez Navarro, the Spanish ninth seed who edged Ana Konjuh 7-6, (7-5) 6-3.
Also reaching the last 16 were Daria Kasatkina, Svetlana Kuznetsova, Elina Svitolina, Monica Puig, Kirsten Flipkens and Johanna Konta.
In the men's singles, Monday's early round of 32 winners included Japan's Taro Daniel, who beat Great Britain's Kyle Edmund 6-4, 7-5, and Spaniard Roberto Bautista Agut, who was a 7-6 (7-2) 6-2 winner over Paolo Lorenzi.
Slovakia's Andrej Martin was given a walkover when his opponent, Phillip Kohlschreiber of Germany, withdrew.