title: 2021 Open de Oeiras IV – Singles
text: # 2021 Open de Oeiras IV – Singles
  
  Carlos Alcaraz was the defending champion but chose not to defend his title.
  
  Gastão Elias won the title after defeating Holger Rune 5–7, 6–4, 6–4 in the final.
  
  ## Seeds
  
  * Mathias Bourgue (first round)
  * Wu Tung-lin (second round)
  * Julian Lenz (second round)
  * Tseng Chun-hsin (second round)
  * Roberto Quiroz (first round)
  * Carlos Gimeno Valero (quarterfinals)
  * Pedro Cachin (first round)
  * Riccardo Bonadio (second round)
  
  ## 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
  
  | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
  | - | - | - | - | - | - | - | - | - |
  | | Gastão Elias | 4 | 7 | 0 | | | | |
  | | Nuno Borges | 6 | 5 | $0^r$ | | | | |
  | | Nuno Borges | 6 | 5 | $0^r$ | Gastão Elias | 5 | 6 | 6 |
  | | | | | | Holger Rune | 7 | 4 | 4 |
  | | Holger Rune | 6 | 3 | 6 | Holger Rune | 7 | 4 | 4 |
  | Q | Timofey Skatov | 2 | 6 | 2 | | | | |
  
  ### Top half
  
  | First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
  | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
  | 1 | M Bourgue | 2 | 2 | | | | | | | | | | | | | | | |
  | WC | Pedro Araújo | 6 | 6 | | WC | P Araújo | 5 | 0 | | | | | | | | | | |
  | | G Elias | 6 | 6 | | | G Elias | 7 | 6 | | | | | | | | | | |
  | WC | Luís Faria | 2 | 3 | | | | | | | | G Elias | $6^0$ | 6 | 6 | | | | |
  | | C Ugo Carabelli | 6 | 6 | | | | | | | | C Ugo Carabelli | $7^7$ | 3 | 0 | | | | |
  | | J de Jong | 4 | 2 | | | C Ugo Carabelli | 4 | 7 | 6 | | | | | | | | | |
  | | J Forejtek | $6^4$ | 6 | 0 | 8 | R Bonadio | 6 | 5 | 4 | | | | | | | | | |
  | 8 | R Bonadio | $7^7$ | 3 | 6 | | | | | | | | | | | G Elias | 4 | 7 | 0 |
  | 4 | C-h Tseng | 6 | 6 | | | | | | | | | | | | N Borges | 6 | 5 | $0^r$ |
  | | R Ortega Olmedo | 4 | 2 | | 4 | C-h Tseng | 3 | 6 | 1 | | | | | | | | | |
  | | J Härteis | 3 | 0 | | Q | FC Jianu | 6 | 3 | 6 | | | | | | | | | |
  | Q | FC Jianu | 6 | 6 | | | | | | | Q | FC Jianu | 4 | 4 | | | | | |
  | | N Serdarušić | 4 | 5 | | | | | | | | N Borges | 6 | 6 | | | | | |
  | Q | D Yevseyev | 6 | 7 | | Q | D Yevseyev | $7^7$ | 4 | 2 | | | | | | | | | |
  | | N Borges | 6 | 6 | | | N Borges | $6^2$ | 6 | 6 | | | | | | | | | |
  | 5 | R Quiroz | 3 | 0 | | | | | | | | | | | | | | | |
  
  ### Bottom half
  
  | First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
  | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
  | 6 | C Gimeno Valero | 6 | 6 | | | | | | | | | | | | | | | | |
  | | V Sachko | 2 | 1 | | 6 | C Gimeno Valero | 6 | 6 | | | | | | | | | | | |
  | PR | V Galović | 4 | $7^7$ | 6 | PR | V Galović | 4 | 2 | | | | | | | | | | | |
  | | D Ajduković | 6 | $6^4$ | 1 | | | | | | 6 | C Gimeno Valero | 2 | 4 | | | | | | |
  | | H Rune | 6 | 6 | | | | | | | | H Rune | 6 | 6 | | | | | | |
  | | T van Rijthoven | 3 | 4 | | | H Rune | 5 | 6 | 6 | | | | | | | | | | |
  | Alt | C Denolly | 4 | 0 | | 3 | J Lenz | 7 | 4 | 3 | | | | | | | | | | |
  | 3 | J Lenz | 6 | 6 | | | | | | | | | | | | | H Rune | 6 | 3 | 6 |
  | 7 | P Cachin | 4 | 7 | $6^1$ | | | | | | | | | | | Q | T Skatov | 2 | 6 | 2 |
  | | G Oliveira | 6 | 5 | $7^7$ | | G Oliveira | 3 | 1 | | | | | | | | | | | |
  | | I Sijsling | 6 | 2 | $6^4$ | Q | T Skatov | 6 | 6 | | | | | | | | | | | |
  | Q | T Skatov | 2 | 6 | $7^7$ | | | | | | Q | T Skatov | $7^7$ | 5 | 6 | | | | | |
  | | G Blancaneaux | 3 | 2 | | | | | | | Q | N Sánchez Izquierdo | $6^4$ | 7 | 1 | | | | | |
  | Q | N Sánchez Izquierdo | 6 | 6 | | Q | N Sánchez Izquierdo | 6 | $7^7$ | | | | | | | | | | | |
  | WC | T Cação | 1 | 1 | | 2 | T-l Wu | 2 | $6^2$ | | | | | | | | | | | |
  | 2 | T-l Wu | 6 | 6 | | | | | | | | | | | | | | | | |
  