Brazil to start with a bang
Former World Cup coach MILOVAN RAJEVAC gives his take on this weekend's big matches at Russia 2018
The complexion of this game has changed significantly in the past 24 hours, with Spain sacking Julen Lopetegui and replacing him with technical director Fernando Hierro yesterday.
He is a big name, but having managed just one season in the Spanish second tier with Real Oviedo, I think he lacks the top level coaching experience which is essential for managing a national team.
It is difficult to predict how La Furia Roja will respond to the change; they might pull together or they might just implode - Portugal will be a good early indicator.
Spain's fluent possession game should cause Fernando Santos' ageing centre-backs all sorts of problems but Portugal's attacking players can worry Spain's backline as well.
The Portuguese are strongest in attacking midfield where they have tricky players like Bernardo Silva and Goncalo Guedes supporting Cristiano Ronaldo.
Much of the spotlight on France has shone on Paul Pogba after a mixed season at Manchester United.
But I think he will thrive under the pressure, he's just that sort of player.
His form for the Red Devils is in the past and he will be fully focused on Les Bleus.
I expect Pogba to pull the strings in midfield behind a front three of, if fit, Kylian Mbappe, Antoine Griezmann and Olivier Giroud.
Should they help France score first, expect to see Les Bleus find the net a few more times.
But, if Australia grab a shock lead, things can get very difficult for France as the Socceroos can be quite hard to break down.
Argentina will come into their clash with Iceland cold, having seen two of their World Cup warm-up matches against Nicaragua and Israel cancelled.
That means that La Albiceleste have played only one match, a 4-0 win over Haiti, since being hammered 6-1 by Spain in March. Argentina's World Cup preparations have been a gamble, and their chances now rest on the form of their talisman Lionel Messi and the atmosphere and harmony within the squad.
If the team spirit is good, they can go far in Russia. Iceland's disciplined side will be a perfect test of an Argentina team that failed to score in three of their last five World Cup qualifiers.
In recent friendlies, Joachim Loew's Germany haven't been as impressive as their World Cup holders tag suggests.
They have won just one of their friendlies, a narrow 2-1 victory over Saudi Arabia, since wrapping up their World Cup qualifying campaign with a 100 per cent record.
But as 2014 World Cup winner Philipp Lahm said last month: "Germany have always been a tournament team."
Die Mannschaft may not have impressed in their warm-up matches but they are the best in the world when it comes to focus, determination and character.
I expect Loew to start with a front four of Timo Werner, Thomas Mueller, Mesut Oezil and either Julian Draxler or Marco Reus.
Mexico are a very passionate team,they will fight like warriors, but quality is on Germany side's.
Brazil coach Tite's main selection poser is whether to stick with a more solid midfield axis of Fernandinho, Paulinho and Casemiro, or drop one of them to accommodate Brazil's fab four.
In their final warm-up game, a 3-0 win over Austria, Tite left out Fernandinho and slotted Philippe Coutinho in midfield behind a front three of Neymar, Willian and Gabriel Jesus.
It worked well, but I think Tite will opt for the more cautious option in their opener. Still, I can't see this Swiss team coping with Brazil's attack.
Expect a goal-fest.
- Milovan Rajevac coached Ghana at the 2010 World Cup, where they were a penalty shoot-out away from becoming the first African nation to reach the semi-finals. Now coach of Thailand, Rajevac has been tasked with spearheading the War Elephants' charge towards the global stage. He was speaking to Dilenjit Singh.