The 2021 Croatia Open (also known as the Plava Laguna Croatia Open Umag for sponsorship reasons) is a men's tennis tournament played on outdoor clay courts. It is the 31st edition of the Croatia Open, and part of the 250 Series of the 2021 ATP Tour. It take place at the International Tennis Center in Umag, Croatia, from 19 through 25 July 2021.[1] [2]
See main article: 2021 Croatia Open Umag – Singles.
Carlos Alcaraz def. 
Richard Gasquet, 6–2, 6–2See main article: 2021 Croatia Open Umag – Doubles.
Fernando Romboli / David Vega Hernández def. 
Tomislav Brkić / 
Nikola Ćaćić, 6–3, 7–5| Event | W | F | SF | QF | Round of 16 | Round of 32 | width=85 | Q | width=85 | Q2 | width=85 | Q1 |
| Singles | 250 | 150 | 90 | 45 | 20 | 0 | 12 | 6 | 0 | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubles | 0 |
| Event | W | F | SF | QF | Round of 16 | Round of 32 | width=85 | Q2 | width=85 | Q1 |
| Singles | €41,145 | €29,500 | €21,000 | €14,000 | €9,000 | €5,415 | €2,645 | €1,375 | ||
| Doubles* | €15,360 | €11,000 | €7,250 | €4,710 | €2,760 |
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Spain | Albert Ramos Viñolas | 41 | 1 | |
| Serbia | Dušan Lajović | 43 | 2 | |
| Serbia | Filip Krajinović | 44 | 3 | |
| France | Richard Gasquet | 54 | 4 | |
| Aljaž Bedene | 56 | 5 | ||
| Spain | Jaume Munar | 66 | 6 | |
| Spain | Carlos Alcaraz | 72 | 7 | |
 Italy | Gianluca Mager | 73 | 8 |
The following players received wildcards into the main draw:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
Salvatore Caruso → replaced by 
Renzo Olivo
Taro Daniel → replaced by 
Andrej Martin Lorenzo Musetti → replaced by Carlos Taberner| Country | Player | Country | Player | Rank1 | Seed | |
|---|---|---|---|---|---|---|
| Bosnia and Herzegovina | Tomislav Brkić | Serbia | Nikola Ćaćić | 101 | 1 | |
| Pablo Cuevas | France | Fabrice Martin | 165 | 2 | ||
| Brazil | Rafael Matos |  Belarus | Andrei Vasilevski | 165 | 3 | |
 Venezuela, Bolivarian Republic of | Luis David Martínez |  New Zealand | Artem Sitak | 195 | 4 |
The following pairs received wildcards into the doubles main draw:
Simone Bolelli / Máximo González → replaced by Damir Džumhur / Antonio Šančić