Serena stays in hunt, Djokovic loses in doubles
DEFENDING champion Serena Williams ended a three-match losing streak against France's Alize Cornet to keep her hopes of a fifth Olympic gold medal alive on Monday.
But it was a rollercoaster 7-6 (7-5), 6-2 victory for the 34-year-old world No. 1 who 24 hours earlier had suffered her first-ever Olympic women's doubles loss with sister Venus.
Cornet defeated the American three times in 2014, including at Wimbledon, and proved to be a thorn in her opponent's side again in Rio.
Williams stepped on the gas in the second set to secure a third-round clash with Ukraine's Elina Svitolina.
Juan Martin del Potro followed up his shock defeat of Novak Djokovic by downing Portugal's Joao Sousa.
The 27-year-old, ranked 141 in the world after years of wrist injury pushed him to the brink of quitting, swept to a 6-3, 1-6, 6-3 win.
Things got even better for del Potro when French fifth seed Jo-Wilfried Tsonga, a potential quarter-final opponent, lost 6-4, 6-3 to Gilles Muller of Luxembourg.
Japan's fourth seed Kei Nishikori wrapped up the day with a 7-6 (7-4), 6-4 win over Australia's John Millman.
Del Potro eventually ran out of steam when he and Maximo Gonzalez lost their men's doubles second-round tie to Rafael Nadal and Marc Lopez.
The 6-3, 5-7, 6-2 scoreline gave the Spanish pair a quarter-final spot.
Djokovic suffered a second Olympic defeat in the space of 24 hours when he and Nenad Zimonjic were knocked out of the men's doubles.
The Serbs lost 6-4, 6-4 to Brazilian fourth seeds Marcelo Melo and Bruno Soares.