Milos Raonic, the world number 22, will miss the US Open due to a glute injury.
Rafael Nadal – a four-time winner of the ATP Masters 1000 tournament – overcame Dan Evans in straight sets on Wednesday.
Three-time grand slam champion Stan Wawrinka outclassed Grigor Dimitrov in straight sets on day one of the ATP 1000 event in Montreal.
Stefanos Tsitsipas was too good for Australian Jordan Thompson, prevailing 6-3 7-6 (7-4) to book a spot in the last eight on Thursday.
As five seeds fell at the Citi Open, Stefanos Tsitsipas and Nick Kyrgios were second-round winners.
Kyle Edmund let a two-set lead slip against Fernando Verdasco, while Stan Wawrinka also lost as Wimbledon champion Novak Djokovic advanced.
Felix Auger-Aliassime will beat Rafael Nadal, Roger Federer and Novak Djokovic, according to Stefanos Tsitsipas.
There will be a new champion at Queen's Club after Marin Cilic bowed out on a great day for Felix Auger-Aliassime.
Felix Auger-Aliassime will battle with compatriot Milos Raonic for a place in the final of the Stuttgart Open.
Runner-up at the 2018 Stuttgart Open, Milos Raonic continued his comeback from injury by beating Jo-Wilfried Tsonga in Germany on Wednesday.