Martinez has always lined up Belgium in a 3-4-3 which can be changed into 3-4-2-1 depending on the situation or even a very defensive 5-4-1/5-3-2. Not a lot of options in the centre back area, but if anyone gets injured Martinez can deploy Witsel as an emergency centre back and it will not be surprising to see Witsel as a centre back. As for starters, Vertonghen/Vermaelen, Alderwiereld and Denayer start as centre backs. Castange and Carrasco would be the right and left wingbacks respectively.
I don’t see any changes in the tactics or formation other than personnel changes.
Even after the loss of their captain and a leader Vincent Kompany, Belgium’s defence looks very experienced and is still up to the mark. They have the duo of Alderwiereld and Vertonghen who have a lot of experience playing together at Spurs. Their decision making in crucial moments as well as the understanding between them is important in a post Kompany era.
Other options include Thomas Vermaelan who is also an experienced veteran and Jason Denayer. Denayer is the only player who has recovery pace in his locker and whose technical abilty will prove useful as a libero. That role could also be taken by anyone of Vermaelen or Vertonghen or Alderwiereld.
Belgium have some very versatile Wingbacks in Castange and Carrasco. With lack of any orthodox wingers available for Belgium so their role will become more important. Castange has the ability to play at both wings and not compromise with the quality of the service. Castange has also played as fullbacks as well if they substitute one of the centre backs.Thomas Meunier is also a great option to play as wingback.
Yannick Carrasco who is an outright winger has been excellent for Ateltico even if he was moved to play as left wing back and he would have to do same in Euro’s. His pace, control of possession, positional awareness makes him a perfect wingback and would be told to move forward to play as winger as well.
More likelier than not however, Martinez will rely upon Thomas Meunier as his right wing back. Vastly experienced and able to defend and get forward in equal measure, he has become a cornerstone of Belgium's flank play. His height and strength makes him a complete asset to have in that back 5.
On the left, aside from Carrasco - the other option is Thorgan Hazard, who brings the advantage of a telepathic relationship with his brother Eden. He is a right footed inverted winger in truth but he has the diligence and work-rate that Carrasco is beginning to lack at this stage of his career.
Expect to see... Belgium’s 5 at the back would be Vertonghen, Alderwiereld, Denayer, Meunier and Hazard.
Witsel has really grown as a footballer in recent years. There was much hype about him when he first broke through yet many were left scratching their head as to what he brought to the table when watching him for Belgium. After his move to Dortmund he has blossomed, both on a technical level and a tactical level. His leadership has also been impressive and this has translated into his performances for the national side... he is a rock that this team can depend on.
Game controller/DLPNext to him will most likely by Youri Tielemans, who has had an outstanding season at club level. Whilst he too has developed his leadership skills and ability to 'compete' in a midfield battle, one thing that he has always had is his ability to pick a pass and glide out of difficult situations with the ball. This will ensure that Belgium have a smooth passage of the ball from defence to attack regardless of the pressure they face.
Expect to see... Witsel anchoring and Tielemans in a regista role, or even both of them in a box to box type of role.
No other player might not be under more pressure than Eden Hazard. His £100M deal to Real Madrid has not worked like many predicted and is considered as a big flop. So all eyes would be on him to make a mark on this tournament which will provide him the platform to get things going for his club. He is great at the wings and especially good in 1v1 situations, but he is very destructive in those half channels as well. A dribbler with great goal scoring abilities.
Romelu Lukaku has had a very up and down career so far. Considered as one of the best at Everton he was bought by Manchester United where he completely flopped and people trolled his ability to take first touch as one of the worst first touches. He moves to Inter where Conte utilises him as a second striker who drops deep to collect the ball and hold it until other players arrive and he is among goals now. Due to his high physical strength, defenders find it difficult to push him off the ball.
Lukaku’s form for Belgium has never dipped since Roberto Martinez took over. He has played in the same system and has the same role for Belgium as he done under Conte in Inter. Mertens is a sure short starter in this Belgium squad. He is another one who is really destructive when he gets into thos half channels in possession. Belgium also have Michy Batshuayi and Christian Benteke in the squad. Benteke has scored around 7 goals in the last 7-8 games of the season, so he is coming in with form.
At the heart of it all will be Kevin De Bruyne. The world's greatest playmaker has shrugged off a facial injury and will look to hit the ground running after a heart-breaking loss to Chelsea in the Champions League Final. He will have freedom to roam under Martinez, much more so than under Guardiola who usually restricted him to the right half space. His killer passing and goal scoring from range will be on display no doubt.
Expect to see... Lukaku and De Bruyne combining down the right or centrally whilst Eden Hazard holds the width down the left or left half space.
Belgium have a more complete squad and in terms of quality they are a close second to the France team. This squad can certainly bring in the trophy home to Belgium but against big teams in big competitions on a big stage, this team seems to capitulate and end up losing the game getting them knocked out. In 2016 Euro they lost against Wales in the quarter final which they should have won easily.
In the World Cup they lost 1-0 to a Messi driven Argentina in 2014 and same thing happened against France in the 2018 semis. If they face off against France before final and manage to defeat them, then probably no one can stop them from winning the whole thing. I predict they will win the whole thing if they can just defeat France in any round.