Semifinal questions: How do Belgium counter France's front three? England speed or Croatia possession?

The World Cup has reached the semifinal stage and it's an all-European affair, with France facing Belgium on Tuesday, followed by Croatia vs. England the following day.

Ahead of the final four, here is one key question that each team must answer.

France: Can Giroud tee up Griezmann and Mbappe?

France have reached the semifinals by overcoming decent opposition in Argentina and Uruguay, yet it still feels like they have not entirely clicked. Kylian Mbappe has produced one stunning performance against Argentina -- perhaps the best individual display of the entire competition -- while Antoine Griezmann has provided decisive moments without really playing well. Do les Bleus have an extra gear?

Mbappe and Griezmann are clearly their most dangerous attackers, but perhaps the key man is Olivier Giroud. Playing upfront and, as ever, with his back to goal, he is essentially a permanent decoy and assister, rather than a goal scorer. His knock-downs and flick-ons have worked on, particularly as a substitute against Australia, but he has been less impressive in the past couple of games, although he did assist Mbappe's second against Argentina after a lovely team move.

Against Belgium, Giroud will face familiar opponents: Tottenham's Toby Alderweireld, Manchester City's Vincent Kompany and, possibly, his former Arsenal teammate Thomas Vermaelen. Giroud cannot defeat those defenders in terms of speed, but his teammates can. As such, his approach will be relatively straightforward: Position himself in front of a defender, hope to prise them out of their defensive line and create space for Griezmann and Mbappe.

Kompany, whose positioning was somewhat uncertain against Brazil, is particularly prone to getting involved in physical confrontations and leaving space in behind, which means the Giroud vs. Kompany clash might be the game's pivotal individual battle.

Belgium: What system does Martinez use?

Having used a 3-4-3 formation throughout Belgium's first four World Cup matches, Roberto Martinez surprisingly switched to a midfield diamond, or a 4-3-3 with Kevin De Bruyne as a false nine, for the 2-1 quarterfinal victory over Brazil. The system, though, was not a complete success: Belgium conceded plenty of chances, with the flexible nature of their defence sometimes being pulled apart.

Martinez faces a formation dilemma ahead of the semifinal, complicated by his only proper wing-back, Thomas Meunier, being ruled out through suspension. With attacking options like Nacer Chadli and Yannick Ferreira-Carrasco the alternatives, and the speed of France right-winger Kylian Mbappe to cope against, a three-man defence seems risky.

Therefore, it's more likely that Martinez will play four at the back, with Jan Vertonghen as a conventional left-back. The manager can be more attacking on the opposite side, with only the functional, defense-minded Blaise Matuidi to worry about. As such, Chadli might be used at right-back, which would be his fourth position of the tournament.

Marouane Fellaini started against Brazil and was tasked with pushing wide to support Meunier. On Tuesday, he might be asked to do something similar to the left, in order to shut down Mbappe. Axel Witsel will play in holding midfield and Mousa Dembele could come into the side with Chadli, who played centrally vs. Brazil, being used elsewhere.

That would leave De Bruyne to play in the front three again, drifting away from Samuel Umtiti and Raphael Varane in the central position. Eden Hazard would be on the left while Romelu Lukaku might again play from the right, against Lucas Hernandez. With Martinez, however, you often have to expect the unexpected.

England: Can they cope with Croatia's possession play?

Gareth Southgate has shown little interest in deviating from his 3-3-2-2 formation, despite the danger of Jordan Henderson being overrun in the centre of the pitch, with one exception. In the closing stages vs. Colombia, England's manager summoned Eric Dier to help protect the defence, but the move coincided with the team's poorest spell of the game. Things improved after Henderson returned to the holding role, so there's minimal temptation to disturb the system by introducing Dier vs. Croatia.

This is, nevertheless, a new test. Thus far, England have largely avoided opponents hoping to outplay them in midfield. Colombia were hampered by the absence of James Rodriguez and instead packed the lineup with holding midfielders, while Sweden, Tunisia and Panama played on the break and the Belgium match was essentially irrelevant as both managers fielded reserve sides.

Croatia, though, have talented midfielders who will command possession; in their 2-2 draw with Russia, Luka Modric and Ivan Rakitic spread into very wide positions, almost full-back zones. Manager Zlatko Dalic is likely to reformat his side on Wednesday, opting for a 4-3-3 rather than a 4-4-2 but, if anything, Modric and Rakitic will have more license to play wider.

This will presumably stretch England's own midfield trio and, if Dele Alli and Jesse Lingard need to play wider, there's a danger that Henderson will be left exposed to the movement inside of Ante Rebic and Ivan Perisic. England won't be entirely unhappy if Croatia dominate possession, as they should be able to play on the counterattack. Coping with long spells of pressure, though, will make things nervy.

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Croatia: Do they have enough speed?

Facing England brings two major problems. The first is their unusual system. The second is the sheer level of speed. Croatia should be intelligent enough to cope with the former concern, but the latter problem might be unsolvable.

The chief threat is Raheem Sterling, who twice sped in behind the opposition defence against Sweden before failing to finish, albeit once when he was in an offside position anyway. But Croatia use a more aggressive defensive line than Sweden and their defenders might be overawed by England's pace.

This could be a particular problem if Sime Vrsaljko, who limped off vs. Russia, is ruled out through injury. The Atletico Madrid right-back is, by a distance, Croatia's most mobile defender and exerted a major influence upon their play with his overlapping against the host nation. Without him, it is likely that Domagoj Vida would switch to right-back and Vedran Corluka would come into the side at centre-back, alongside Dejan Lovren.

Corluka and Lovren are both very experienced, but would hardly make the speediest centre-back pairing. Corluka's lack of pace was a concern the best part of a decade ago; he is simply not comfortable turning and running. Lovren, meanwhile, struggled massively against a Harry Kane-inspired Tottenham in Liverpool's 4-1 loss to Tottenham at Wembley last October and was hauled off after half an hour.

Croatia have also played 120 minutes in both the round of 16 and the quarterfinal, meaning tiredness will be a major problem throughout the side, not merely at the back. With Kane, Sterling, Jesse Lingard and Dele Alli all threatening to run in behind and Henderson capable of lifting passes over the top, England's main route to goal looks promising.