Greek star Stefanos Tsitsipas reached the last 16 at the Shanghai Masters after beating Alexandre Muller 6-3 7-5 on Tuesday. It is the fourth time this year that Tsitsipas has made this stage of an ATP tournament but it will be his first meeting in almost a year with last-16-opponent Daniil Medvedev. In other action, Gael Monfils defeated French compatriot Ugo Humbert 7-6 (7-6), 2-6, 6-1 as the 38-year-old became the second oldest player ever to reach the last 16 in Shanghai. “It’s never easy to play Ugo, he’s really aggressive, playing fast off both wings and takes a lot of time from you,” sa…