| Doubles | |
|---|---|
| 2021 Cary Challenger II | |
| Champions |  William Blumberg Max Schnur |
| Runners-up | Stefan Kozlov  Peter Polansky |
| Score | 6–4, 1–6, [10–4] |
Christian Harrison and Dennis Novikov were the defending champions [1] but lost in the semifinals to William Blumberg and Max Schnur.
Blumberg and Schnur won the title after defeating Stefan Kozlov and Peter Polansky 6–4, 1–6, [10–4] in the final.
Lloyd Glasspool / Nicholas Monroe (first round) Evan King / Jackson Withrow (first round) Robert Galloway / Alex Lawson (first round) Christian Harrison / Dennis Novikov (semifinals)| First round | Quarterfinals | Semifinals | Final | ||||||||||||||||||||||||
| 1 | L Glasspool N Monroe | 2 | 5 | ||||||||||||||||||||||||
| W Blumberg M Schnur | 6 | 7 | W Blumberg M Schnur | 7 | 6 | ||||||||||||||||||||||
| Mi Redlicki D Young | 3 | 64 |  T Fancutt J Kubler | 5 | 1 | ||||||||||||||||||||||
| T Fancutt J Kubler | 6 | 77 | W Blumberg M Schnur | 3 | 6 | [10] | |||||||||||||||||||||
| 4 | C Harrison D Novikov | 6 | 6 | 4 | C Harrison D Novikov | 6 | 1 | [5] | |||||||||||||||||||
| WC | Robin Catry Damien Salvestre | 3 | 4 | 4 | C Harrison D Novikov | 4 | 6 | [10] | |||||||||||||||||||
| Alt | S Kirchheimer  S Mochizuki | 6 | 3 | [10] | Alt | S Kirchheimer S Mochizuki | 6 | 3 | [4] | ||||||||||||||||||
 G Brouwer R Stalder | 4 | 6 | [7] | W Blumberg M Schnur | 6 | 1 | [10] | ||||||||||||||||||||
| WC | Garrett Johns Sean Sculley | 4 | 4 | S Kozlov P Polansky | 4 | 6 | [4] | ||||||||||||||||||||
JC Aragone  N Barrientos | 6 | 6 | JC Aragone N Barrientos | 4 | 4 | ||||||||||||||||||||||
| S Kozlov P Polansky | 6 | 6 | S Kozlov P Polansky | 6 | 6 | ||||||||||||||||||||||
| 3 | R Galloway A Lawson | 1 | 2 | S Kozlov P Polansky | 64 | 7 | [10] | ||||||||||||||||||||
 J Jung M Krueger | 78 | 3 | [10] | J Jung M Krueger | 77 | 5 | [4] | ||||||||||||||||||||
| WC | Brian Cernoch M Kiger | 66 | 6 | [5] | J Jung M Krueger | 6 | 62 | [12] | |||||||||||||||||||
| Alt | A Bolt R Hijikata | 79 | 65 | [12] | Alt | A Bolt R Hijikata | 4 | 77 | [10] | ||||||||||||||||||
| 2 | E King J Withrow | 67 | 77 | [10] | |||||||||||||||||||||||
Dennis Novikov won the all American final, beating Ryan Harrison 6–4, 7–5
This was the first edition of the tournament.
Jared Donaldson was the defending champion, but he lost in the first round to Alex Bolt.
Nicolas Mahut was the defending champion and successfully defended his title, defeating Gilles Müller in the final, 6–4, 6–4.
Novak Djokovic defeated Kei Nishikori in the final, 6–3, 7–5 to win the men's singles tennis title at the 2016 Rogers Cup. It was his record 30th Masters 1000 title and his record 43rd Masters 1000 final. He did not lose a single set in the entire tournament.
Johan Brunström and Frederik Nielsen were the defending champions but only Nielsen chose to defend his title, partnering Noah Rubin. Nielsen lost in the first round to Blaž Rola and Grega Žemlja.
Nick Kyrgios was the defending champion, but withdrew before the tournament began.
Stefan Kozlov was the defending champion but chose not to defend his title.
Dennis Novikov was the defending champion but lost in the third round to Renzo Olivo.
Roberto Maytín and Jackson Withrow were the defending champions but chose to defend their title with different partners. Maytín partnered Robert Galloway but lost in the first round to Filip Peliwo and Roy Smith. Withrow partnered Martin Redlicki and successfully defended his title.
Andrey Golubev and Aleksandr Nedovyesov were the defending champions but chose not to defend their title.
Mitchell Krueger and Jack Sock were the defending champions but chose not to defend their title.
Teymuraz Gabashvili and Dennis Novikov were the defending champions but only Novikov chose to defend his title, partnering Christian Harrison. Novikov successfully defended his title.
Diego Hidalgo and Martin Redlicki were the defending champions but chose not to defend their title.
Treat Huey and Nathaniel Lammons were the defending champions but chose not to defend their title.
Ruben Gonzales and Ruan Roelofse were the defending champions but chose to defend their title with different partners. Gonzales partnered Hunter Johnson but lost in the first round to Hans Hach Verdugo and Miguel Ángel Reyes-Varela. Roelofse partnered Christopher Rungkat but lost in the quarterfinals to William Blumberg and Max Schnur.
Mitchell Krueger and Blaž Rola were the defending champions but lost in the first round to William Blumberg and Max Schnur.
Robert Galloway and Alex Lawson were the reigning champions but chose to defend their title with different partners. Galloway partnered Jackson Withrow but lost in the final to William Blumberg and Max Schnur. Lawson partnered Reese Stalder but lost in the semifinals to Galloway and Withrow.
Orlando Luz and Rafael Matos were the defending champions but chose not to defend their title.
William Blumberg and Max Schnur were the defending champions but chose to defend their title with different partners. Blumberg partnered Jackson Withrow but lost in the first round to Anirudh Chandrasekar and Vijay Sundar Prashanth. Schnur partnered Treat Huey but lost in the first round to Julian Cash and Henry Patten.