The Italian seed defeats American Ben Shelton, 6-4, 7-6 (7-1)

Sinner, Alcaraz race through to the next stage

Muchova silenced a capacity crowd to beat Olympic champion Zheng in straight sets

They push each other to the limit in the latest chapter of burgeoning rivalry

The Italian world number one twice tested positive for banned substance clostebol

Sabalenka and Zheng are on course to meet in the semi-final

Swiatek, Sinner both qualify for 2nd round after beating their opponents

World number eight overcame Frenchman Luca Van Assche 4-6, 6-3, 6-4, firing 15 aces

Sixth seed outlasted Baptiste 7-6 (8/6), 7-6 (7/3) to reach second round

Despite winning 24 Grand Slam titles, the Serbian tennis star has yet to secure an Olympic gold