St. Petersburg 2021 ATP
Final
| Winner | Loser | Score | |
|---|---|---|---|
| Marin Cilic | d. | Taylor Fritz | 7-6(3) 4-6 6-4 |
Semifinals
| Winner | Loser | Score | |
|---|---|---|---|
| Taylor Fritz | d. | Jan Lennard Struff | 5-7 6-1 6-3 |
| Marin Cilic | d. | Botic Van De Zandschulp | 6-3 6-3 |
Quarterfinals
| Winner | Loser | Score | |
|---|---|---|---|
| Jan Lennard Struff | d. | Denis Shapovalov | 6-4 6-3 |
| Taylor Fritz | d. | John Millman | 6-4 6-2 |
| Marin Cilic | d. | Roberto Bautista Agut | 6-4 3-6 6-3 |
| Botic Van De Zandschulp | d. | Andrey Rublev | 6-3 6-4 |
Round of 16
| Winner | Loser | Score | |
|---|---|---|---|
| Denis Shapovalov | d. | Pablo Andujar | 2-6 6-3 6-0 |
| Jan Lennard Struff | d. | Alexander Bublik | 6-4 6-3 |
| John Millman | d. | Aslan Karatsev | 6-3 6-2 |
| Taylor Fritz | d. | Tommy Paul | 7-6(3) 6-4 |
| Marin Cilic | d. | Karen Khachanov | 6-4 6-7(1) 6-4 |
| Roberto Bautista Agut | d. | Mackenzie Mcdonald | 6-3 6-2 |
| Botic Van De Zandschulp | d. | Sebastian Korda | 6-2 7-5 |
| Andrey Rublev | d. | Ilya Ivashka | 6-4 6-4 |
Round of 32
| Winner | Loser | Score | |
|---|---|---|---|
| Pablo Andujar | d. | Federico Delbonis | 6-2 7-6(1) |
| Jan Lennard Struff | d. | James Duckworth | 7-6(3) 6-3 |
| Alexander Bublik | d. | Evgenii Tiurnev | 6-3 6-4 |
| John Millman | d. | Yshai Oliel | 6-1 6-1 |
| Tommy Paul | d. | Pedro Martinez | 6-3 6-2 |
| Taylor Fritz | d. | Emil Ruusuvuori | 6-1 6-4 |
| Karen Khachanov | d. | Adrian Mannarino | 6-3 6-3 |
| Marin Cilic | d. | Albert Ramos | 6-2 6-3 |
| Mackenzie Mcdonald | d. | Egor Gerasimov | 7-5 6-4 |
| Sebastian Korda | d. | Nino Serdarusic | 7-6(2) 7-5 |
| Botic Van De Zandschulp | d. | Yoshihito Nishioka | 6-2 6-2 |
| Ilya Ivashka | d. | Laslo Djere | 6-3 6-2 |
Qualifying round 2
| Winner | Loser | Score | |
|---|---|---|---|
| Yoshihito Nishioka | d. | Miomir Kecmanovic | 6-3 4-6 6-2 |
| Egor Gerasimov | d. | Radu Albot | 7-6(2) 6-4 |
| Emil Ruusuvuori | d. | Dmitry Popko | 7-6(2) 6-4 |
| Botic Van De Zandschulp | d. | Evgeny Donskoy | 5-7 6-3 6-2 |
Qualifying round 1
| Winner | Loser | Score | |
|---|---|---|---|
| Yoshihito Nishioka | d. | Roman Safiullin | 7-5 6-2 |
| Miomir Kecmanovic | d. | Evgeny Karlovskiy | 2-6 6-4 6-1 |
| Egor Gerasimov | d. | Damir Dzumhur | 6-1 7-6(6) |
| Radu Albot | d. | Federico Coria | 6-3 6-4 |
| Emil Ruusuvuori | d. | Gilles Simon | 6-0 6-3 |
| Dmitry Popko | d. | Benjamin Bonzi | 4-6 7-6(4) 6-2 |
| Evgeny Donskoy | d. | Mikael Ymer | 6-2 7-5 |
| Botic Van De Zandschulp | d. | Marc Polmans | 6-6 RET |