Barcelona teenager Ansu Fati has been added to Spain's U21 squad for Tuesday's game against Montenegro.
Defending champions Germany will again meet Spain in the Under-21 European Championship final after both won their semifinals on Thursday.
Germany shocked Spain to win the Euro 2017 title as Mitchell Weiser's header clinched glory.
El Mundo Deportivo reported that Barcelona would target Saul to bolster their midfield should they fail to sign Marco Verratti.
Saul Niguez scored a second-half hat trick to fire Spain into the final of the European Under-21 Championship with a 3-1 victory over 10-man Italy.
Nick Miller asks the biggest questions facing England, Germany, Spain and Italy in the European Under-21 Championship semifinals on Tuesday.
"The truth is that right now the market is complex because there are very expensive transfers being made, but the clause is the one I have," he said.
England will face Germany in the semifinals of the European Under-21 Championship, while Italy take on Spain.
Real Madrid forward Marco Asensio is on the right path to becoming a world class player, according to Spain under-21 teammate Dani Ceballos.
Spain's Hector Bellerin has said he will donate £50 to victims of the Grenfell Tower fire for every minute he plays at the European U21 Championship.
Athletic Bilbao defender Yeray Alvarez has left Spain's under-21 squad after a medical check-up revealed that his testicular cancer has returned.