Spain manager Vicente Del Bosque has admitted that Xabi Alonso's absence may force him into a change of formation for the Confederations Cup later this month.
Alonso's partnership with Sergio Busquets at the base of the midfield has been one of the keys to Spain's success under Del Bosque, who said that may give him greater flexibility to select a more attacking midfield, as he did in the 2-1 friendly victory over Haiti on Saturday.
"Our team has been based on Xabi Alonso and Busquets," he told a press conference on Monday.
"This solution is what has brought calm to the team. Without Xabi we will need to look for an alternative, we will see if we want to be more offensive like against Haiti with (Javi) Martinez on his own and Cesc (Fabregas) and (Juan) Mata further forward, or a more defensive option."
The Haiti match was most notable for the return of captain Iker Casillas as he took to the field for the first time since January and completed the first 45 minutes before being replaced by Pepe Reina.
Del Bosque confirmed that Victor Valdes will start Tuesday's friendly against the Republic of Ireland to ensure all three keepers have had a runout before their Confederations Cup campaign starts against Uruguay on Sunday.
"I have found all three goalkeepers in very good shape. It is our desire that all of them play so tomorrow Victor will play."
The 62-year-old also confirmed that David Villa will feature against the Irish after Fernando Torres and Roberto Soldado were given their chance against Haiti.
"The same thing will happen with the strikers, the other day two played and tomorrow Villa will play.
"We have insisted that we want to try all of the players and the final decision we will take later on."