2023 National Bank Open – Men's singles
Jannik Sinner defeated Alex de Minaur in the final, 6–4, 6–1 to win the men's singles title at the 2023 Canadian Open. It was his first ATP Tour Masters 1000 title and eighth ATP Tour singles title overall.
Pablo Carreño Busta was the reigning champion, but withdrew before the tournament began due to injury.
Seeds
The top eight seeds received a bye into the second round.Draw
Finals
Seeded players
The following are the seeded players. Seedings are based on ATP rankings as of 31 July 2023. Rank and points before are as of 7 August 2023.| Seed | Rank | Player | Points before | Points defending | Points won | Points after | Status | |||
| 1 | 1 |  Withdrawn playersThe following players would have been seeded, but withdrew before the tournament began.
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