| 2021 San Marino Open | |
|---|---|
| Date | 9–15 August |
| Edition | 28th |
| Location | City of San Marino, San Marino |
| Champions | |
| Singles | |
 Holger Rune | |
| Doubles | |
 Zdeněk Kolář /  Luis David Martínez | |
The 2021 San Marino Open was a professional tennis tournament played on clay courts. The 28th edition of the tournament, which was part of the 2021 ATP Challenger Tour, took place in City of San Marino, San Marino between 9 and 15 August 2021.
| Country | Player | Rank1 | Seed |
|---|---|---|---|
 ITA | Marco Cecchinato | 84 | 1 |
 FRA | Gilles Simon | 102 | 2 |
| ITA | Salvatore Caruso | 111 | 3 |
 BOL | Hugo Dellien | 139 | 4 |
| ITA | Federico Gaio | 147 | 5 |
 ARG | |||
| ARG | Sebastián Báez | 156 | 7 |
 SLO | Blaž Rola | 173 | 8 |
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw using a protected ranking:
The following player received entry into the singles main draw as an alternate:
The following players received entry from the qualifying draw:
Francesco Forti 
Orlando Luz Manuel Mazza Julian Ocleppo The following player received entry as a lucky loser:
Holger Rune def. Orlando Luz 1–6, 6–2, 6–3. Zdeněk Kolář / Luis David Martínez def. Rafael Matos / João Menezes 1–6, 6–3, [10–3].The 2019 JC Ferrero Challenger Open was a professional tennis tournament played on clay courts. It was the second edition of the tournament which was part of the 2019 ATP Challenger Tour. It took place in Alicante, Spain between 1 and 7 April 2019.
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