When the draw for the group stage of the 2018 FIFA World Cup was made, the match between Spain and Portugal on the borders of the Black Sea looked as if it would decide which of the two sides would finish top of Group G.
However, 24 hours before kick-off it has taken on a whole new significance. Real Madrid announced that the Spanish national side coach Julen Lopetegui would take charge of the club in July. The Spanish football federation, RFEF wasted no time in sacking him on Wednesday. A few hours later, RFEF director of sport Fernando Hierro was named as his replacement.
Hierro was a great player for Real Madrid and Spain in his day, but has only one season's experience as the first team coach of second division Oviedo.
With less than 48 hours before Spain kick off their World Cup campaign against the 2016 European champions, it is hard to imagine what changes Hierro can make to the tactics Lopetegui had been using in preparation for Russia.
David de Gea is certain to start in goal, while in defence, Jordi Alba, Gerard Pique and Sergio Ramos are fixtures, with the only doubt being whether the more attack minded Alvaro Odriozola or the adaptable and ever-reliable Nacho Fernandez is given the task of playing at right back where they will have to defend against Portugal captain Cristiano Ronaldo.
Spain's last preparation game, a 1-0 win at home to Tunisia on June 9 left some doubts in midfield with Koke and Thiago Alcantara expected to battle it out for a place alongside Sergio Busquets, David Silva, Andres Iniesta and possibly Isco.
That started the debate over whether Lopetegui would pick Diego Costa as a central striker or use the pace and mobility of Iago Aspas and Rodrigo Moreno against a solid, organised, but aging Portugal defence.
Hierro is bound to have his own ideas on this, but with such short notice he probably won't have time to implement them and he will have to go with whatever Lopetegui had planned. Spain's lack of punch in the first half against Tunisia implies he will probably go with Koke in midfield and perhaps with Costa and Aspas in attack and Isco starting on the bench.
Predicting the Spain starting 11 was a guessing game before Lopetegui was sacked. Hierro's job now is working on the morale and unity of a squad that must be in shock after seeing the man who led them undefeated for the past two years shown the door on the eve of the most important football tournament in the world.
The first obstacle for Spain is Portugal, who will be making their seventh appearance at the World Cup and their fifth in a row.
Their best performance came on their debut in 1966, when they finished third after losing to hosts England in the semi-finals.
But their title win at the Euro 2016 has been their best moment in recent years. But after the euphoria of winning Euro 2016, even the most ardent aficionado of Portugal would admit that their victory was largely unexpected and was achieved in a pragmatic, attritional style under the guidance of Fernando Santos.
Portugal's playing style totally contrasts Spain, who like to play technical, skillful and free-flowing football.
Santos will also be under pressure, having dropped the ever-present Nani (the third most capped player in Portugal's history), the hero of the Euro 2016 final, Eder, and the Barcelona pair of Nelson Semedo and Andre Gomes. A Portugal team without these four would have been unthinkable a few short months ago.
New attacking talent comes in the form of Andre Silva and Goncalo Guedes, who will be hoping to replace the likes of Nani and Quaresma in the near future.
Portugal's system is built on a solid defence with relatively few goalscoring chances being created, in the hope that Ronaldo will need just half a chance to score. The 33-year-old talisman has formed an impressive partnership with Silva and their link-up play will be vital if Portugal are to have a successful tournament.
As Portugal's all-time record appearance maker and goalscorer, Ronaldo is unquestionably the leader of the team, and has scored for his country in their last seven major tournaments.
Ronaldo will be up against some of his Real Madrid clubmates, who will be eager to get Spain back on track after the coach's change.