2021 National Bank Open

The 2021 Canadian Open (branded as the 2021 National Bank Open presented by Rogers for sponsorship reasons) were outdoor hard court tennis tournaments played from August 6 to August 15, 2021, as part of the 2021 US Open Series. The men's event took place at the Aviva Centre in Toronto, and the women's tournament at the IGA Stadium in Montreal. It was the 131st edition of the men's tournament—a Masters 1000 tournament on the 2021 ATP Tour, and the 119th edition of the women's tournament—a WTA 1000 tournament on the 2021 WTA Tour.

They were originally scheduled to be played from August 8 to August 16, 2020, as part of the 2020 tennis season. Due to the COVID-19 pandemic, the 2020 edition of the Canadian Open was postponed to 2021 by Tennis Canada.

Impact of the COVID-19 pandemic, postponement to 2021
The men's and women's tournaments alternate between Toronto and Montreal annually. On April 11, 2020, pursuant to a request by the province of Quebec (the COVID-19 pandemic in Quebec was the centre of the first wave of the pandemic in Canada) for all cultural and sporting events to be cancelled through August, Tennis Canada announced that the women's half of the Canadian Open, as part of the 2020 WTA Tour, would be postponed and held in Montreal in 2021.

The men's half of the event was still tentatively scheduled, but was still at risk of cancellation or postponement if the ATP and WTA extended their suspension of play into August, or if Toronto or the province of Ontario made a similar order that also applies to the period. Toronto had already cancelled all city-led major events, festivals, conferences, permits and cultural programs until June 30, 2020. Although subject to provincial restrictions on public gatherings, Mayor John Tory stated that these did not necessarily bar the hosting of sporting events.

On June 17, 2020, Tennis Canada officially announced that the men's tournament had also been postponed to 2021, citing logistical and safety issues that would be present for players and staff even if the event were to be held behind closed doors, including a federal health order requiring 14 days self-isolation upon arrival for anyone travelling to Canada. As they have been postponed, the men's and women's tournaments will still be held in Toronto and Montreal as per the traditional rotation.

On February 1, 2021, National Bank was promoted to title sponsor of the tournament, replacing Rogers Communications, which now serves as presenting sponsor.

Prize money

 * per team

Men's singles

 * 🇷🇺 Daniil Medvedev def. 🇺🇸 Reilly Opelka, 6–4, 6–3.

Women's singles

 * 🇮🇹 Camila Giorgi def. 🇨🇿 Karolína Plíšková, 6–3, 7–5.

This was Giorgi's third WTA Tour singles title, and first at WTA 1000 level.

Men's doubles

 * 🇺🇸 Rajeev Ram / 🇬🇧 Joe Salisbury def. Nikola Mektić /  Mate Pavić, 6–3, 4–6, [10–3]

Women's doubles

 * 🇨🇦 Gabriela Dabrowski / 🇧🇷 Luisa Stefani def. Darija Jurak /  Andreja Klepač, 6–3, 6–4

Seeds
The following are the seeded players. Rankings are as of August 2, 2021. Points before are as of August 9, 2021.

Because the tournament is being held one week later than the last edition in 2019 and as a result of special ranking adjustment rules due to COVID, the Points before column already reflects either a 50% reduction in the player's 2019 points or the substitution of the player's next best result. Accordingly, the Points defending column has been adjusted to show the greater of (a) 50% of the player's 2019 points and (b) the player's 19th best result.

Following the tournament, players will count either their 2021 points or 50% of their 2019 points, whichever is greater.

In addition, because the tournament is not mandatory in 2021, players may count their next best result instead if that result is better. Accordingly, points after will differ from points before only if the player's 2021 points won exceed points defending.

† Due to a change in schedule for the 2021 tournament and COVID ranking adjustment rules, the Points defending column reflects the greater of (a) 50% of the player's 2019 points and (b) the player's 19th best result. Instances of the latter are enclosed in parentheses.

‡ Because the 2021 tournament was non-mandatory, the player substituted his 19th best result instead of the points won in this tournament.

Other entrants
The following players received wild cards into the main singles draw:
 * 🇺🇸 Jenson Brooksby
 * 🇦🇺 Nick Kyrgios
 * 🇨🇦 Vasek Pospisil

The following player received entry using a protected ranking into the main singles draw:
 * 🇯🇵 Kei Nishikori

The following player received entry using a special exempt into the main singles draw:
 * 🇺🇸 Mackenzie McDonald

The following players received entry from the singles qualifying draw:
 * 🇱🇹 Ričardas Berankis
 * 🇦🇺 James Duckworth
 * 🇯🇵 Yoshihito Nishioka
 * 🇺🇸 Tommy Paul
 * 🇫🇮 Emil Ruusuvuori
 * 🇨🇦 Brayden Schnur

The following players received entry as lucky losers:
 * 🇪🇸 Feliciano López
 * 🇺🇸 Frances Tiafoe

Withdrawals

 * Before the tournament
 * 🇮🇹 Matteo Berrettini → replaced by 🇩🇪 Jan-Lennard Struff
 * 🇪🇸 Pablo Carreño Busta → replaced by 🇫🇷 Benoît Paire
 * Borna Ćorić → replaced by 🇦🇺 John Millman
 * 🇷🇸 Novak Djokovic → replaced by 🇷🇸 Dušan Lajović
 * Roger Federer → replaced by 🇷🇸 Miomir Kecmanović
 * 🇧🇪 David Goffin → replaced by 🇪🇸 Albert Ramos Viñolas
 * 🇪🇸 Rafael Nadal → replaced by 🇪🇸 Feliciano López
 * 🇦🇹 Dominic Thiem → replaced by 🇺🇸 Taylor Fritz
 * 🇨🇦 Milos Raonic → replaced by Lloyd Harris
 * Stan Wawrinka → replaced by Marin Čilić
 * 🇩🇪 Alexander Zverev → replaced by 🇺🇸 Frances Tiafoe


 * During the tournament
 * 🇯🇵 Kei Nishikori

Seeds

 * Rankings are as of August 2, 2021.

Other entrants
The following pairs received wildcards into the doubles main draw:
 * 🇨🇦 Félix Auger-Aliassime / 🇨🇦 Alexis Galarneau
 * 🇧🇬 Grigor Dimitrov / 🇨🇦 Vasek Pospisil
 * 🇨🇦 Peter Polansky / 🇨🇦 Brayden Schnur

The following pair received entry as alternates:
 * 🇷🇸 Miomir Kecmanović / 🇳🇴 Casper Ruud

Withdrawals

 * Before the tournament
 * 🇧🇬 Grigor Dimitrov / 🇨🇦 Vasek Pospisil → replaced by 🇷🇸 Miomir Kecmanović / 🇳🇴 Casper Ruud
 * 🇪🇸 Marcel Granollers / 🇦🇷 Horacio Zeballos → replaced by 🇦🇹 Oliver Marach / 🇦🇹 Philipp Oswald
 * Wesley Koolhof / Jean-Julien Rojer → replaced by  Wesley Koolhof / 🇺🇸 Austin Krajicek
 * 🇷🇸 Filip Krajinović / 🇷🇸 Dušan Lajović → replaced by 🇷🇺 Aslan Karatsev / 🇷🇸 Dušan Lajović
 * 🇩🇪 Jan-Lennard Struff / 🇩🇪 Alexander Zverev → replaced by Marin Čilić / 🇩🇪 Jan-Lennard Struff

Seeds

 * 1 Rankings are as of August 2, 2021

Other entrants
The following players received wild cards into the main singles draw:
 * 🇨🇦 Leylah Annie Fernandez
 * 🇷🇴 Simona Halep
 * 🇨🇦 Rebecca Marino
 * 🇺🇸 Sloane Stephens
 * 🇨🇦 Carol Zhao

The following players received entry from the singles qualifying draw:
 * 🇺🇸 Amanda Anisimova
 * 🇫🇷 Clara Burel
 * 🇬🇧 Harriet Dart
 * 🇫🇷 Océane Dodin
 * 🇫🇷 Caroline Garcia
 * 🇨🇿 Tereza Martincová
 * 🇷🇺 Anastasia Potapova
 * 🇧🇪 Alison Van Uytvanck

Withdrawals

 * Before the tournament
 * 🇷🇺 Ekaterina Alexandrova → replaced by 🇨🇿 Kateřina Siniaková
 * 🇦🇺 Ashleigh Barty → replaced by 🇺🇸 Danielle Collins
 * Belinda Bencic → replaced by Jil Teichmann
 * 🇺🇸 Jennifer Brady → replaced by 🇮🇹 Camila Giorgi
 * 🇺🇸 Sofia Kenin → replaced by Anastasija Sevastova
 * 🇩🇪 Angelique Kerber → replaced by 🇦🇺 Ajla Tomljanović
 * 🇨🇿 Barbora Krejčiková → replaced by 🇨🇿 Marie Bouzková
 * 🇯🇵 Naomi Osaka → replaced by 🇫🇷 Fiona Ferro
 * 🇵🇱 Iga Świątek → replaced by 🇷🇺 Liudmila Samsonova
 * 🇨🇿 Markéta Vondroušová → replaced by 🇨🇳 Zhang Shuai


 * During the tournament
 * 🇬🇧 Johanna Konta (left knee injury)

Retirements

 * 🇨🇿 Marie Bouzková (dizziness)
 * 🇨🇿 Tereza Martincová (abdominal pain)
 * 🇷🇺 Anastasia Potapova (left ankle injury)
 * 🇨🇳 Zhang Shuai (left leg injury)

Seeds

 * Rankings are as of August 2, 2021.

Other entrants
The following pairs received wildcards into the doubles main draw:
 * 🇨🇦 Mélodie Collard / 🇨🇦 Carol Zhao
 * 🇨🇦 Leylah Annie Fernandez / 🇨🇦 Rebecca Marino

The following pairs received entry as alternates:
 * 🇬🇧 Harriet Dart / 🇪🇪 Anett Kontaveit
 * 🇫🇷 Océane Dodin / 🇷🇺 Kamilla Rakhimova

Withdrawals

 * Before the tournament
 * 🇨🇿 Marie Bouzková / 🇨🇿 Lucie Hradecká → replaced by 🇫🇷 Elixane Lechemia / 🇺🇸 Ingrid Neel
 * Chan Hao-ching / Latisha Chan → replaced by 🇩🇪 Vivian Heisen / 🇵🇱 Alicja Rosolska
 * 🇺🇸 Kaitlyn Christian / 🇯🇵 Nao Hibino → replaced by 🇺🇸 Kaitlyn Christian / 🇺🇸 Christina McHale
 * 🇰🇿 Anna Danilina / 🇧🇾 Lidziya Marozava → replaced by 🇳🇴 Ulrikke Eikeri / 🇺🇸 Catherine Harrison
 * 🇯🇵 Eri Hozumi / 🇨🇳 Zhang Shuai → replaced by 🇫🇷 Océane Dodin / 🇷🇺 Kamilla Rakhimova
 * 🇯🇵 Miyu Kato / 🇺🇸 Sabrina Santamaria → replaced by 🇺🇸 Emina Bektas / 🇬🇧 Tara Moore
 * 🇨🇿 Barbora Krejčíková / 🇨🇿 Kateřina Siniaková → replaced by Beatrice Gumulya / 🇬🇧 Emily Webley-Smith
 * 🇺🇸 Sofia Kenin / Jeļena Ostapenko → replaced by  Jeļena Ostapenko / 🇺🇦 Dayana Yastremska
 * 🇷🇺 Anastasia Potapova / 🇷🇺 Vera Zvonareva → replaced by 🇬🇧 Harriet Dart / 🇪🇪 Anett Kontaveit