Openers inevitably carry great gravitas as they tend to shape the group but given the potential trickiness of both Iran and Morocco, neither of these two giants can afford a slip up.
It’s a blockbuster clash with some of the best players in the world on show and with that in mind, we compare and contrast some of key protagonists.
CRISTIANO RONALDO V DIEGO COSTA
Ronaldo is three goals shy of Ferenc Puskas 84-goal haul for Hungary which stands as the most ever by a European player.
Few will doubt the Real Madrid forward’s chances of breaking yet another record in Russia after an absurd goalscoring streak in 2018 – he notched 22 of his 26 La Liga goals after the turn of the year.
At 33, he remains the spearhead and source of goals for his country and his immense physical conditioning means he’ll arrive for the Spain clash in peak shape – a fearsome prospect for club team-mate Sergio Ramos and bitter rival Gerard Pique.
A big-game mentality has hallmarked his club career, but he’s struggled to translate that reputation onto the international stage having only scored once against seven of the eight World Cup winners in 22 appearances (he’s never faced Uruguay). Look for him to lay down a marker in Sochi.
For Spain, the number nine has been dominating the thoughts of former boss Julen Lopetegui as if it were some mathematical equation but with no obvious answer, the probability is Costa will lead the line regardless of who occupies the touchline.
He often has looked out of place for La Roja, though. The Atletico Madrid striker is a demolition man, behind him in contrast are architects and he very often tears down their attacking constructs with poor passing and wayward ball control.
He’s a vice and virtue quality, however, as Costa batters defenders and inevitably gaps appear for the likes of David Silva and Isco to exploit.
With Spain likely deploying a 4-3-3, those two flanking Costa will be expected to create works of art out of the rubble of their striker’s destruction.
Pepe and Bruno Alves sit in the heart of Portugal’s defence and at a combined age of 71, could be in for a turbulent night.
BERNARDO SILVA V ISCO
Andres Iniesta is in the dying embers of his marvellous Spain career but the carousel of creative talent will see Isco step up to prominence in Russia.
While he’s been largely mystifying for Madrid, struggling to gain the complete trust of Zinedine Zidane particularly in the early part of last season, with Spain he has truly come alive.
The 26-year-old’s stunning hat-trick in the not-so-friendly trouncing of Argentina saw him move onto a respectable 10 goals in 27 international outings.
While debate has raged over who occupies the No9 shirt, the topic could be completely inconsequential because they have enough playmakers to create chances and Isco could be the man they look to for a finish. Portugal are a sit-in-and-counter side and so Isco will be tasked with unpicking a resolute defence.
Similarly, Bernardo Silva has endured a season punctuated by an inconsistent run of games but unlike Isco, he retains the confidence of Pep Guardiola and it led to a string of impressive outings.
He’s one of a trio of Portugal players tipped as the heir to Ronaldo – Goncalo Guedes and Andre Silva the other two – and has on occasion lined up slightly behind the skipper.
Fernando Santos will likely to revert him back to the right-hand side and Manchester City observers will be well aware of his quality as he drifts in from wide positions.
Nicknamed ‘Bubblegum’ for the way in which the ball is glued to his feet, he is quick of thought and skill. Having missed the Euro 2016 triumph through injury, he’ll be desperate to make his mark and there’s no better way to start than against Spain
GONCALO GUEDES V MARCO ASENSIO
Asensio is unlikely to start for Spain but curiously that doesn’t actually lessen his potential impact.
The fixture could turn out to be a tactical chessmatch and there is every chance Spain could struggle to make inroads.
If that is the case, Asensio is an ace card, capable of producing moments of magic when it matters most.
The 22-year-old has proven as much throughout his fledgling but flourishing Real Madrid career, scoring in a Champions League final while goals arrived against heavy hitters like Bayern Munich and Barcelona last season.
He’s fast, tricky and melds those talents to a mallet left-foot which form the perfect make-up of an impact sub.
Likewise, Guedes might be another young star to begin this tournament on the bench. Santos is an arch pragmatist so it remains to be seen whether he is bold enough to partner Ronaldo with Guedes in his starting XI or opt for the more tested Andre Silva.
Guedes, though, is fresh from a stunning season on loan at Valencia and scored twice in last week’s warm-up win over Algeria.
What he lacks in international pedigree, the 21-year-old makes up for in enterprise and if Santos wants to relieve some of the goalscoring burden from Ronaldo’s shoulders, Guedes is an enticing option.
Either way, he may have something to say in this game, the question is whether it be from the bench or the start.
Jose Mourinho thinks England have what it takes for a strong showing at the World Cup.
Premier League pedigree and Champions League experience should make up for the Three Lions’ youthfulness, said the Manchester United boss, who has seen four of his Reds picked for the side.
Speaking to Sky Sports News, the Portuguese said: “They have a good group of young but experienced players.
“All of them play in the best domestic competition in the world, the Premiership, all of them playing for the best teams, all of them with experience of playing Champions League, which is a high level of football, obviously.
“So I think yes, I think they can do it.”
Mourinho suggested favourites like Germany, France and Brazil should not be seen as shoo-ins based on how they look on paper.
“They have good squads but good squads don’t always make good teams,” he added.
Mourinho did not say explicitly if he thought England will go all the way, although he previously predicted Gareth Southgate’s men will make it out of the group stage.
However he predicted heartache for the national team soon after, with defeat by Brazil in the quarter finals.
After their humiliating 7-1 semi-final defeat to Germany in 2014, the South Americans will be hoping to recover their pride.
“It’s a big match,” he said on Tuesday in his capacity as an RT pundit, quipping: “It’s not bad that for me (that) my players go on holiday.”
Ashley Young says England are already raring to go for next week’s World Cup opener against Tunisia.
The Three Lions have won their opening fixture just once in the last four World Cups, squeezing past Paraguay 1-0 in 2006, but lost to Italy four years ago following 1-1 draws with the United States (2010) and Sweden (2002).
They were also held by an unfancied Russia in their first outing at Euro 2016, but Manchester United full-back Young insists the current crop are ready to make an early statement this time.
Tunisia await in Volgograd on Monday and England are ready to take the game to their Group G rivals.
“It is always important to make a good start to a tournament. You want to get off to winning ways,” said Young.
“We are fully prepared and ready for that first game. You can talk about our results historically but we are here and we are looking to do well in training and do well in that first match. I think you can see from the last two games we have started brightly and on the front foot and if you start like that it can put teams on the back foot and that is what we are looking to do come the first game.”
Tunisia are ranked 21st in the world by FIFA, nine places below England, and served notice of their resilience against Spain at the weekend in a creditable 1-0 defeat.
England, meanwhile, won both of their warm-ups against Nigeria and Costa Rica on the back of lively first-half performances.
“I saw the game on Saturday night and they were good, but every team at the World Cup is a good team,” said Young.
“You have to play against the team in front of you and it is going to be a tough task but we are fully prepared for that.
“Obviously there is more pressure because this is a World Cup but every player in the squad has dealt with pressure. We have to show we can handle that.
“As a kid you want to play in the biggest tournaments and I am as excited as anyone out there.”