Juan Mónaco was the defending champion, but lost to John Isner in the semifinals.
Isner went on to win the title, defeating Nicolás Almagro in the final, 6–3, 7–5.
Austin Krajicek and John Peers were the defending champions, but Peers chose not to compete.
Krajicek paired with Mitchell Krueger but lost in the semifinals to eventual finalists Bradley Klahn and Michael Venus.
Frank Dancevic and Peter Polansky won the title 7–5, 6–3.
Dudi Sela and Harel Srugo were the defending champions but decided not to participate.
Bradley Klahn and Michael Venus won the final against Adam Feeney and John-Patrick Smith 6–3, 6–4.
Australian pairing of Thanasi Kokkinakis and Benjamin Mitchell defeated compatriots Alex Bolt and Andrew Whittington, 6–3, 6–2, to be the inaugural champions.
This is the first edition of the event.
David Ferrer was the three-time defending champion, but lost in the semifinals to Lu Yen-hsun.
Bradley Klahn and Michael Venus were the defending champions, however Venus chose not to participate. Klahn partnered with Matt Reid and won the title, defeating Marcus Daniell and Artem Sitak in the final, 4–6, 6–4, [10–7].
Gilles Müller was the defending champion, but lost in the second round to Matthew Ebden.
Cameron Norrie was the defending champion but chose not to defend his title.
Rafael Nadal defeated Stefanos Tsitsipas in the final, 6–2, 7–6(7–4), to win his fourth Rogers Cup title.
Novak Djokovic defeated Roger Federer in the final, 6–4, 6–4, to win the men's singles title at the 2018 Cincinnati Masters. With the win, he became the first player to complete the career Golden Masters in singles.
David Goffin was the defending champion, but withdrew before the competition began.
This was the first edition of the tournament.
Marin Čilić was the defending champion, but lost in the second round to Diego Schwartzman.
Richard Gasquet was the defending champion, but lost to Jordan Thompson in the semifinals.
Evgeny Karlovskiy was the defending champion but lost in the first round to Stefan Kozlov.
Steve Johnson was the defending champion, but lost in the first round to Christopher Eubanks.
Bradley Klahn was the defending champion but chose not to defend his title.
Defending champion Rafael Nadal successfully defended his title, defeating Daniil Medvedev in the final, 6–3, 6–0, to win the men's singles title at the 2019 Canadian Open. This was the first time Nadal defended a hardcourt title.
Bernard Tomic was the defending champion, but retired in the first round of the qualifying tournament against Denis Istomin.
Daniel Cox 
Marius Copil 
Sergiy Stakhovsky 
