Two-time US Open quarterfinalist out of Flushing Meadows.
Karen Khachanov beat the same opponent twice in one day.
World No. 1 names four players on level of Big 3.
Milos Raonic has two very good reasons to sustain a strict safety bubble.
Six-time US Open champion offers simple reason for elevating training game.
Felix Auger-Aliassime brought back the burn.
Stefanos Tsitsipas points out the positive of life in US Open bubble.
