Victory in combination with a draw in the other match between Germany and Ukraine would be sufficient for Luis Enrique’s side to progress.
Regardless of what happens, La Roja will get a second shot at the task on Tuesday, when they play host to Joachim Low’s side.
Switzerland, meanwhile, are bottom of the group but have not been whipping boys. The two matches they have lost came by just a single goal, including a 1-0 defeat in Spain to an early Mikel Oyarzabal strike.
Furthermore, a couple of draws against Germany show that they carry a threat.
Enrique will be forced into at least one change from the side that drew with the Netherlands. Gaya is missing because of a head knock and will be replaced by Tottenham’s Sergio Reguilon.
Alvaro Morata is liable to be given the nod in attack again after impressing against the Netherlands, with his work rate cited as one of the assets that will be required in Switzerland.
He is expected to be joined in the attack by the in-form Ferran Torres and Oyarzabal.
The midfield, meanwhile, will be anchored by Barcelona’s Sergio Busquets, while club-mate Sergi Roberto will feature at right-back.
The keystone of the operation will be captain Sergio Ramos, who continues to near a world-record mark for caps won, and in goal Manchester United’s David de Gea will be preferred to Chelsea’s Kepa Arrizabalaga.
Goalkeepers: De Gea (Manchester United), Kepa (Chelsea), Simon (Athletic)
Midfielders: Busquets (Barcelona), Koke (Atletico Madrid), Asensio (Real Madrid), Rodri (Manchester City), Fabian (Napoli), Sergi Roberto (Barcelona), Llorente (Atletico Madrid), Merino (Real Sociedad)
Forwards: Canales (Betis), Morata (Juventus), Gerard (Villarreal), Adama (Wolves), Ferran (Manchester City), Olmo (Leipzig), Oyarzabal (Real Sociedad)