Second leg ties of the fourth round of the Spanish cup take place on or around 29th November. (28.09.17)
Results were as follows (aet - after extra time, pso - penalty shoot out, teams qualifying in bold):
| Sevilla Ben Yedder (2), Ganso, Correa |
4-0 | Cartagena |
| Atlético Madrid Giménez, Fernando Torres (2) |
3-0 | Elche |
| Barcelona Alcácer, Piqué, Aleix Vidal, Denis Suárez, José Arnáiz |
5-0 | Real Murcia |
| Real Madrid Borja Mayoral (2) |
2-2 | Fuenlabrada Luis Milla, Portilla |
| Athletic Bilbao |
0-1 | Formentera Alvaro Muñiz |
| Real Sociedad Llorente, Juanmi |
2-3 | Lleida Esportiu Nuñez, Molina (Pen), Radulovic |
| Villarreal Bakambu (2), Bacca |
3-0 | Ponferradina |
| Valencia Santi Mina (2), Robert Ibáñez, Rubén Vezo |
4-1 | Zaragoza Pombo |
| Málaga Adrián González |
1-1 | Numancia Elgezabal |
| Leganés Tito |
1-0 | Valladolid |
| Betis Boudebouz, Tello (2) |
3-5 | Cádiz Barral, Dani Romera (2), Aitor García (Pen), Kecojevic |
| Espanyol Gerard Moreno (Pen), Granero, Sergio García |
3-2 | Tenerife Bryan Acosta, Juan Carlos |
| Alavés Munir (2), Bojan |
3-0 | Getafe |
| Las Palmas Toledo, Rémy |
2-3 | Deportivo Çolak, Borja Valle (2) |
| Levante Morales |
1-1 | Girona Mojica |
| Celta Iago Aspas (Pen) |
1-0 | Eibar |