He has always had a weak return game. But past week or so he has played guys with bombs, and last night played a guy on fire for a set throwing down 130mph 2nd serves. Tsitsipas rode the wave and played the big points like a champion. He is hardly being mentioned. Most people say Medvedev the big danger. From what i am seeing Tsitispas will be very hard to stop. Even for the Great Djokovic.