Group B features two European heavyweights and two resilient sides who are all about defending well. Jamie Pacheco talks us through the four teams and gives us his best tips...
"Spain look made for that sort of challenge. They could come unstuck against the likes of Germany who play such a fast and physical brand of football which could upset their rhythm but they look more than good enough to win a couple of knockout games against just about anyone else."
Spain can win the World Cup at [7.4]. They tick every box that needs to be ticked when looking for a World Cup winner. Excellent qualifying campaign, good experienced manager, strong starting XI, lots of options on the bench, strong defence that keeps plenty of clean sheets, a blend of youth and experience and the know-how of having won tournaments in the past. All the more relevant when you consider players like Sergio Ramos, Gerard Pique, David Silva and Andres Iniesta were all part of those three major tournament wins in 2010, 2012 and 2014.
If there's one area that might be a concern though, it's upfront. It's always a risky strategy to put so much faith in Diego Costa for injury and discipline reasons. Alvaro Morata was left out meaning the two natural understudies - Iago Aspas and Rodrigo - are short of international experience.
Still, Real Madrid pair Marco Asensio and Lucas Vasquez can play upfront as well if really needed.
Another option is to not play an out-and-out striker at all. That's pretty how much how they won Euro 2012.
No-one really expects Portugal to come close to following up their Euro 2016 success. They went on an incredible run there, had an easy route to the final and benefited from two extra-time goals and a penalty shootout win to win their first-ever major title. It's unlikely so much can go their way again.
But everyone will have plenty of respect for them. Not just because of that win but because of the vast experience manager Fernando Santos possesses and the fact that few sides can compete with Portugal in terms of technical ability. Ball-playing centre backs, the ability to effortlessly keep possession, silky skills by the forward men that can unlock a tight game.
Ah yes, they also have Cristiano Ronaldo. Who scored 50+ goals this season for club and country and shows no signs of slowing down in terms of goals. Don't believe the theory that his contract dispute at Real may affect his performances. Few players in the game have ever been as focused as him when it comes to the job in hand.
Are Iran the new Greece? A run of nine clean sheets in 10 matches, just five goals conceded in 18 qualifying games and no defeats in those 18 games suggests their gameplan will be pretty similar.
Carlos Queiroz is in charge and as the man who was Sir Alex Ferguson's number two for so long, briefly Real Madrid manager and a former Portugal coach, that's not a bad guy to have in charge.
They'll look to frustrate, run hard, defend for their lives but as ever with that strategy, might find themselves in a pickle if/when they concede. Playing for 0-0 is always fraught with danger.
Another side who are better at defending than going forward. They didn't t concede a single goal in eight matches in qualifying and were playing the likes of Ivory Coast, Gabon and Mali so that's a better effort than it may first appear.
Unlike Saudi Arabia, they do have players with plenty of experience at big European clubs and that could make a big difference but getting anything from the Group's Big Two still looks a huge task.
Spain are a better all-round team than Portugal and it would be extremely surprising if Fernando Santos' men beat them when they clash in what is their first match. It's worth remembering that Spain's defence will know all about Ronaldo (well, you know what I mean) from playing with and against him in la Liga. The best Portugal can hope for is a draw and if that were the case, you'd expect Spain to score more goals than Portugal against the other two teams and top the group on goal difference.
Either way, there does seem to be a big gulf in class between Portugal and the two outsiders so one way or another the Euro 2016 champs should finish as runners-up here at 11/10.
What do people mean when they say a team is perfect for knock-out football? Well, everyone will have their own views but to me it means that they know how to get over the line and do what's needed to progress. Anything from defending a 1-0 lead to having more stamina in extra time to having the nous, technical skills and bottle to win a penalty shoot-out. A handy bench with pace and goalscoring potential is worth its weight in gold as well when stamina starts to kick in. Sound like anyone we know?
Spain look made for that sort of challenge. They could come unstuck against the likes of Germany who play such a fast and physical brand of football which could upset their rhythm but they look more than good enough to win a couple of knockout games against just about anyone else.
They rate a very solid bet to make the semis at 11/8.