Top seeds Novak Djokovic, Daniil Medvedev, Stefanos Tsitsipas and Alexander Zverev are ready to contend for the 2021 US Open men's singles trophy. In this video, I'll preview their quarters, with dark horses, upset alerts, popcorn matchups and quarterfinal predictions as well as pick a champion.   00:00 Intro 03:20 Novak Djokovic's Quarter 07:53 Alexander Zverev's Quarter 13:40 Stefanos Tsitsipas's Quarter 22:53 Daniil Medvedev's Quarter 27:44 Final Weekend  Sponsors- Rally Tennis: www.rallytennis.com BetUS: www.betus.com.pa/landing.aspx?offer=gillgross&token=GrKCi4IwuQQSW1mZhSUdKGNd7ZgqdRLk