# 2021 US Open – Boys' singles

Jonáš Forejtek was the defending champion, having won the previous edition in 2019, but was no longer eligible to participate in junior events.
Daniel Rincón won the title, defeating Shang Juncheng in the final, 6–2, 7–6$^{(8–6)}$.

## Seeds

All seeds received a bye into the second round.
    01. Shang Juncheng (final)
    02. Samir Banerjee (quarterfinals)
    03. Daniel Rincón (champion)
    04. Bruno Kuzuhara (second round)
    05. Jack Pinnington Jones (second round, retired)
    06. Victor Lilov (quarterfinals)
    07. Viacheslav Bielinskyi (third round)
    08. Jérôme Kym (semifinals)
    09. Mark Lajal (third round)
    10. Sean Cuenin (second round)
    11. Sascha Gueymard Wayenburg (semifinals)
    12. Gonzalo Bueno (second round)
    13. Dali Blanch (second round)
    14. Alejandro Manzanera Pertusa (second round)
    15. Maks Kaśnikowski (third round)
    16. Alexander Bernard (third round)
Click on the seed number of a player to go to their draw section.

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 1 | Shang Juncheng | 3 | 6 | 6 | | | | | | | | | |
| | Pierre Yves Bailly | 6 | 3 | 2 | | | | | | | | | |
| | Pierre Yves Bailly | 6 | 3 | 2 | 1 | Shang Juncheng | 6 | 6 | | | | | |
| | | | | | 11 | Sascha Gueymard Wayenburg | 4 | 4 | | | | | |
| | Petr Nesterov | 6 | 4 | 4 | 11 | Sascha Gueymard Wayenburg | 4 | 4 | | | | | |
| 11 | Sascha Gueymard Wayenburg | 0 | 6 | 6 | | | | | | | | | |
| 11 | Sascha Gueymard Wayenburg | 0 | 6 | 6 | | | | | | 1 | Shang Juncheng | 2 | 6$^6$ |
| | | | | | | | | | | 3 | Daniel Rincón | 6 | 7$^8$ |
| 6 | Victor Lilov | 3 | 1 | | | | | | | | | | | 3 | Daniel Rincón | 6 | 7$^8$ |
| 3 | Daniel Rincón | 6 | 6 | | | | | | | | | | |
| 3 | Daniel Rincón | 6 | 6 | | 3 | Daniel Rincón | 3 | 7$^7$ | 6 | | | | |
| | | | | | 8 | Jérôme Kym | 6 | 6$^4$ | 4 | | | | |
| 8 | Jérôme Kym | 4 | 6 | 6 | 8 | Jérôme Kym | 6 | 6$^4$ | 4 | | | | |
| 2 | Samir Banerjee | 6 | 3 | 4 | | | | | | | | | |

### Top half
#### Section 1

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 1 | J Shang | 7$^7$ | 6 | | | | | | | | | | |
| WC | Aidan Mayo | 6 | 6 | | WC | A Mayo | 6$^5$ | 3 | | | | | | | | | | |
| Q | Miguel Gomes | 3 | 3 | | | | | | | 1 | J Shang | 7$^7$ | 6 | | | | | |
| | Daniel Mérida | 7$^7$ | 6 | | | | | | | | D Mérida | 6$^5$ | 4 | | | | | |
| | Aleksander Orlikowski | 6$^4$ | 3 | | | D Mérida | 6 | 7$^7$ | | | | | | | | | | |
| | | | | | 13 | D Blanch | 3 | 6$^2$ | | | | | | | | | | |
| | | | | | | | | | | | | | | 1 | J Shang | 3 | 6 | 6 |
| | | | | | | | | | | | | | | | PY Bailly | 6 | 3 | 2 |
| | | | | | 12 | G Bueno | 0 | 3 | | | | | | | | | | |
| | Jack Anthrop | 4 | 7$^7$ | 4 | | PY Bailly | 6 | 6 | | | | | | | | | | |
| | Pierre Yves Bailly | 6 | 6$^2$ | 6 | | | | | | | PY Bailly | 6 | 6 | | | | | |
| WC | Colton Smith | 7$^7$ | 6 | | | | | | | WC | C Smith | 4 | 4 | | | | | |
| | Edas Butvilas | 6$^4$ | 4 | | WC | C Smith | 6$^5$ | 6 | 2 | | | | | | | | | |
| | | | | | 5 | J Pinnington Jones | 7$^7$ | 4 | 0$^r$ | | | | | | | | | |

#### Section 2

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 4 | B Kuzuhara | 3 | 6 | 3 | | | | | | | | | |
| Q | Jakub Menšík | 6 | 6 | | Q | J Menšík | 6 | 4 | 6 | | | | | | | | | |
| | Måns Dahlberg | 4 | 2 | | | | | | | Q | J Menšík | 6$^3$ | 4 | | | | | |
| | Petr Nesterov | 6 | 6$^4$ | 6 | | | | | | | P Nesterov | 7$^7$ | 6 | | | | | |
| Q | Philip Florig | 1 | 7$^7$ | 3 | | P Nesterov | 6 | 6 | | | | | | | | | | |
| | | | | | 14 | A Manzanera Pertusa | 4 | 4 | | | | | | | | | | |
| | | | | | | | | | | | | | | | P Nesterov | 6 | 4 | 4 |
| | | | | | | | | | | | | | | 11 | S Gueymard Wayenburg | 0 | 6 | 6 |
| | | | | | 11 | S Gueymard Wayenburg | 7$^7$ | 3 | 6 | | | | | | | | | |
| WC | Ryan Colby | 7 | 4 | 4 | WC | R Colby | 6$^3$ | 6 | 3 | | | | | | | | | |
| | Álvano Guillén Meza | 5 | 6 | 0$^r$ | | | | | | 11 | S Gueymard Wayenburg | 7 | 7$^7$ | | | | | |
| | Ozan Colak | 6$^5$ | 6 | 6$^9$ | | | | | | 7 | V Bielinskyi | 5 | 6$^3$ | | | | | |
| | Abedallah Shelbayh | 7$^7$ | 3 | 7$^{11}$ | | A Shelbayh | 5 | 4 | | | | | | | | | | |
| | | | | | 7 | V Bielinskyi | 7 | 6 | | | | | | | | | | |

### Bottom half
#### Section 3

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 6 | V Lilov | 7$^7$ | 4 | 6 | | | | | | | | |
| Q | Sebastian Dominko | 4 | 6 | 3 | | P Sekulic | 6$^2$ | 6 | 2 | | | | | | | | |
| | Philip Sekulic | 6 | 3 | 6 | | | | | | 6 | V Lilov | 6 | 6 | | | | |
| Q | Christopher Li | 6 | 4 | 6$^5$ | | | | | | 9 | M Lajal | 2 | 2 | | | | |
| WC | Alexander Razeghi | 4 | 6 | 7$^7$ | WC | A Razeghi | 2 | 6 | 3 | | | | | | | | |
| | | | | | 9 | M Lajal | 6 | 4 | 6 | | | | | | | | |
| | | | | | | | | | | | | | | 6 | V Lilov | 3 | 1 |
| | | | | | | | | | | | | | | 3 | D Rincón | 6 | 6 |
| | | | | | 16 | A Bernard | 6 | 7$^7$ | | | | | | | | | |
| | Max Westphal | 6 | 6 | | | M Westphal | 3 | 6$^5$ | | | | | | | | | |
| | Peter Benjamín Privara | 4 | 3 | | | | | | | 16 | A Bernard | 4 | 3 | | | | |
| WC | Aidan Kim | 6 | 6 | | | | | | | 3 | D Rincón | 6 | 6 | | | | |
| | Lui Maxted | 2 | 4 | | WC | A Kim | 6$^4$ | 5 | | | | | | | | | |
| | | | | | 3 | D Rincón | 7$^7$ | 7 | | | | | | | | | |

#### Section 4

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 8 | J Kym | 7$^7$ | 7 | | | | | | | | | | | |
| | Ignacio Buse | 7 | 6 | | | I Buse | 6$^3$ | 5 | | | | | | | | | | | |
| WC | Michael Zheng | 5 | 3 | | | | | | | 8 | J Kym | 6 | 3 | 7$^7$ | | | | | |
| | Adolfo Daniel Vallejo | 6 | 7 | | | | | | | | AD Vallejo | 3 | 6 | 6$^2$ | | | | | |
| Q | Kyle Kang | 4 | 5 | | | AD Vallejo | 6 | 3 | 6 | | | | | | | | | | |
| | | | | | 10 | S Cuenin | 3 | 6 | 3 | | | | | | | | | | |
| | | | | | | | | | | | | | | | 8 | J Kym | 4 | 6 | 6 |
| | | | | | | | | | | | | | | | 2 | S Banerjee | 6 | 3 | 4 |
| | | | | | 15 | M Kaśnikowski | 4 | 6 | 7$^7$ | | | | | | | | | | |
| | Mili Poljičak | 6 | 2 | 1 | | E Quinn | 6 | 0 | 6$^4$ | | | | | | | | | | |
| | Ethan Quinn | 2 | 6 | 6 | | | | | | 15 | M Kaśnikowski | 7 | 2 | 2 | | | | | |
| | Max Hans Rehberg | 4 | 6 | 7$^7$ | | | | | | 2 | S Banerjee | 5 | 6 | 6 | | | | | |
| | Leo Borg | 6 | 3 | 6$^4$ | | MH Rehberg | 0 | 4 | | | | | | | | | | | |
| | | | | | 2 | S Banerjee | 6 | 6 | | | | | | | | | | | |

## Qualifying
### Seeds

* Kalin Ivanovski (first round)
* Coleman Wong (qualifying competition)
* Vilius Gaubas (qualifying competition)
* Adam Jurajda (first round)
* Matthew William Donald (qualifying competition)
* Jakub Menšík (qualified)
* Philip Florig (qualified)
* German Samofalov (first round)
* João Victor Couto Loureiro (qualifying competition)
* Miguel Gomes (qualified)
* Sebastian Dominko (qualified)
* Elmer Møller (first round)

### Qualifiers

* Philip Florig
* Kyle Kang
* Miguel Gomes
* Christopher Li
* Sebastian Dominko
* Jakub Menšík

### Draw
#### First qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 1 | Kalin Ivanovski | 7 | 3 | [3] | | | | |
| WC | Nicholas Heng | 5 | 6 | [10] | | | | |
| WC | Nicholas Heng | 5 | 6 | [10] | WC | Nicholas Heng | 3 | 3$^r$ |
| | | | | | 7 | Philip Florig | 6 | 4 |
| | Derrick Chen | 2 | 2 | | 7 | Philip Florig | 6 | 4 |
| 7 | Philip Florig | 6 | 6 | | | | | |

#### Second qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 2 | Coleman Wong | 7 | 7 | | | | | | |
| WC | Yu Tanaka | 5 | 5 | | | | | | |
| WC | Yu Tanaka | 5 | 5 | | 2 | Coleman Wong | 1 | 6 | [5] |
| | | | | | WC | Kyle Kang | 6 | 3 | [10] |
| WC | Kyle Kang | 7 | 4 | [10] | WC | Kyle Kang | 6 | 3 | [10] |
| 12 | Elmer Møller | 5 | 6 | [6] | | | | | |

#### Third qualifier

| First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 3 | Vilius Gaubas | 6 | 6 | | | | | |
| | Azuma Visaya | 3 | 4 | | | | | |
| | Azuma Visaya | 3 | 4 | 3 | Vilius Gaubas | 6$^3$ | 6 | [3] |
| | | | | 10 | Miguel Gomes | 7$^7$ | 3 | [10] |
| | Orel Kimhi | 5 | 5 | 10 | Miguel Gomes | 7$^7$ | 3 | [10] |
| 10 | Miguel Gomes | 7 | 7 | | | | | |

#### Fourth qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 4 | Adam Jurajda | 4 | 3 | | | | | | |
| | Christopher Li | 6 | 6 | | | | | | |
| | Christopher Li | 6 | 6 | | | Christopher Li | 6 | 5 | [10] |
| | | | | | 9 | João Victor Couto Loureiro | 2 | 7 | [7] |
| | Braden Shick | 6$^5$ | 7$^7$ | [3] | 9 | João Victor Couto Loureiro | 2 | 7 | [7] |
| 9 | João Victor Couto Loureiro | 7$^7$ | 6$^1$ | [10] | | | | | |

#### Fifth qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 5 | Matthew William Donald | 6 | 6$^5$ | [10] | | | | | |
| WC | Sebastian Gorzny | 1 | 7$^7$ | [8] | | | | | |
| WC | Sebastian Gorzny | 1 | 7$^7$ | [8] | 5 | Matthew William Donald | 6 | 1 | [8] |
| | | | | | 11 | Sebastian Dominko | 4 | 6 | [10] |
| | Ezequiel Monferrer | 3 | 4 | | 11 | Sebastian Dominko | 4 | 6 | [10] |
| 11 | Sebastian Dominko | 6 | 6 | | | | | | |

#### Sixth qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 6 | Jakub Menšík | 6 | 3 | [10] | | | | |
| | Neo Niedner | 1 | 6 | [5] | | | | |
| | Neo Niedner | 1 | 6 | [5] | 6 | Jakub Menšík | 6 | 7$^{10}$ |
| | | | | | | Benjamin Kittay | 2 | 6$^8$ |
| | Benjamin Kittay | 6 | 2 | [10] | | Benjamin Kittay | 2 | 6$^8$ |
| 8 | German Samofalov | 4 | 6 | [7] | | | | |