Belgium- Switch to a 4-2-3-1 with Dries Mertens
Before the quarter-finals, many were wary of how Roberto Martinez’s cavalier 3-4-2-1 formation would play against the attacking juggernaut that is Brazil. However, Martinez decided to make tactical changes against the Selecao by playing an additional defensive midfielder in Marouane Fellaini - freeing up Kevin De Bruyne (whose role was almost a false nine), Romelu Lukaku and Eden Hazard. The formation would be best described as an asymmetrical 4-3-3.
Yet, repeating the same formation against France would be a mistake. Les Blues are a great defensive team having only conceded one goal apart from the crazy Argentina Round of 16 games. In the 4-3-3 formation, Nacer Chadli was rather ineffectual as he struggled to fit in as a left-sided central midfielder. Instead, Chadli could be replaced by a proper attacker who might be more effective in breaking down the French defence. Thus, Belgium would be better off returning to one of their original starters: Dries Mertens. Mertens was among the best players in Serie A last season and was similarly effective for the Red Devils earlier in the tournament.
Switching to the 4-2-3-1 would also allow Kevin De Bruyne to function as a roving attacking midfielder, his ideal position (the false nine was ideal against a weaker defence like Brazil). It would also allow Romelu Lukaku to function in his natural role. His role as an inverted winger is effective against aging defenses, something that France certainly are not.
With Hazard and Mertens, Belgium might be defensively vulnerable against France’s fullbacks. However, this won’t be a problem considering Deschamps’s preferred full-backs Lucas Hernandez and Benjamin Pavard are not great offensively. In De Bruyne, Mertens, Lukaku and Hazard, Belgium has the most talented forwards in the tournament. If they use them properly, they could fulfill their potential.