Images, left to right:
Gael Monfils had a match point for the semis but lost his quarterfinal to Kei Nishkori
Madison Keys lost the bronze medal match to Petra Kvitova
Home hope Thomaz Bellucci reached the last eight
World No. 1 Novak Djokovic was stunned by Juan Martin del Potro in his first match
Four-time gold medallist Serena Williams fell in the third round
