It was the second day of the men's tennis competition at the Olympics that saw third seed Stefanos Tsitsipas seventh seed Hubert Hurkacz, eighth seed Diego Schwartzman, 12th seed Karen Khachanov and 16th seed Alejandro Davidovich Fokina advanced.
Mixed fortunes for seeds in second day of action in Tokyo
Tsitsipas had to rally from a break down against Philipp Kohlschreiber before eventually prevailing 6-3, 3-6, 6-3 in one hour, 54 minutes. The Greek won 75 percent of his first serve points on the day.
Zverev rolled past Yen-Hsun Lu 6-1, 6-3, hitting nine aces in the process while Hurkacz needed exactly an hour to knock out Luke Saville 6-2, 6-4. Schwartzman came through against Juan Pablo Varillas 7-5, 6-4 while Khachanov rallied to beat Yoshihito Nishioka 3-6, 6-1, 6-2.
Kei Nishikori gave the hometown fans a thrill with a 6-3, 6-4 upset of Rublev, breaking the fifth seed three times. Auger-Aliassime fell to Max Purcell who replaced Andy Murray 6-4, 7-6 (2). Monfils was edged out by Ilya Ivashka 6-4, 4-6, 7-5.
In matches between non-seeded players, Frances Tiafoe cruised past Soon-woo Kwon 6-3, 6-2, Marcos Giron beat Norbert Gombos 7-6 (4), 3-6, 6-2, Tomas Machac outlasted Joao Sousa 6-7 (5), 6-4, 6-4, Dominik Koepfer rallied past Facundo Bagnis 3-6, 6-3, 7-5, Liam Broady beat Francisco Cerundolo 7-6 (4), 5-7, 6-2, James Duckworth edged Lukas Klein 5-7, 6-3, 7-6 (4) and Daniel Galan eliminated Mohamed Safwat 7-5, 6-1.
Third seeds Juan Sebastian Cabal and Robert Farah advanced past Pablo Carreno Busta and Davidovich Fokina 6-2, 6-4, but fourth seeds Aslan Karatsev and Daniil Medvedev were upset by Klein and Filip Polasek 7-5, 6-4.
Marin Cilic and Ivan Dodig breezed past Taro Daniel and Nishioka 6-2, 6-4, Austin Krajicek and Tennys Sandgren knocked off John Peers and Purcell 3-6, 7-6 (5), [10-5], Marcos Daniell and Michael Venus beat Egor Gerasimov and Ivashka 6-3, 7-6 (6), Lorenzo Musetti and Lorenzo Sonego defeated Pablo Andujar and Roberto Carballes Baena 7-5, 6-4 and Olivier Marach and Philipp Oswald beat John Millman and Saville 7-5, 6-2.