Who do Spain leave out? 2002 repeat for Brazil? France formation change?

EXCLUSIVE: Infantino hopeful 2018 & 2022 World Cups change perception of hosts (1:43)

FIFA president Gianni Infantino tells Gab Marcotti about his hopes that the 2018 and 2022 World Cups change negative perceptions of Russia and Qatar. (1:43)

With 100 days to go until the World Cup kicks off in Russia, ESPN FC reporters around the world address some of the key storylines ahead of the tournament.

GERMANY: Can they repeat as winners?

The holders have questions at left-back and wonder if Joachim Low can create the same harmony and togetherness that underpinned their triumph in Brazil, but these are mere details in comparison with the real issue: die Nationalmannschaft are out to win back-to-back World Cups for the first time since football was broadcast in colour.

The odds are good. Low's squad has depth and variety, most players are at the peak of their powers or have youth on their side and the draw has been kind. So Germany can triumph again; whether they do will come to down to details as well as luck in the knockout stages. But there's no reason not to believe the old adage: A bad Germany makes it to the final. A good Germany wins it. -- Raf Honigstein

SPAIN: Who will be left at home?

This is a recurring dilemma throughout Julen Lopetegui's squad, but up front is where he is most required to cut the Gordian knot. He will look to David Silva, Isco or Marco Asensio for goals when he chooses to play a strikerless/False No.9 formation and, when the tactical approach calls for a centre-forward, Alvaro Morata's seven goals during the coach's two-year unbeaten reign tells you he's the man.

But given the need to complement Morata with the right scoring options, the form of Iago Aspas, Mariano Diaz, Rodrigo, Lucas Vazquez, Santi Mina, Pedro, Gerard Moreno, Vitolo, Aritz Aduriz, Portu, David Villa and Diego "I'm available again" Costa means tough choices must be made. -- Graham Hunter

BRAZIL: 2002 all over again?

A fifth World Cup title looked unlikely in the build up to the tournament. The battle to qualify had gone right to the wire, with three coaches being used, and Inter appeared unable to get centre-forward Ronaldo fit, while Barcelona were adamant that Rivaldo needed an operation and could not play.

Brazil's excellent culture of sports medicine and physical preparation took over, and both stars flew through the competition, tipping the balance in favour of their team. So can doctors and specialists get Neymar back and flying after his operation, ready to lead an exciting squad to title No.6? -- Tim Vickery

ENGLAND: What is Southgate's biggest challenge?

This is a tough one because several problems are rearing their head at the wrong time. Manager Gareth Southgate does not have a settled first-choice goalkeeper, and he has to decide whether Jack Wilshere's talent in midfield outweighs concern over his fitness, while Marcus Rashford's and Adam Lallana's lack of playing time is a concern.

England have two friendlies later this month, against Netherlands and Italy, plus one more on June 2 versus Nigeria, before Southgate must finalise his 23-man squad. As such, he might have to make big decisions without answers to big questions. -- Mark Ogden

FRANCE: Will Deschamps stick to his 4-4-2 formation?

The France head coach doesn't like changing things that work. So far, his 4-4-2 system, with Olivier Giroud and Antoine Griezmann up front, has done well for him, reaching the Euro 2016 final.

However, Giroud isn't playing much this season and, with all the wide players available (Thomas Lemar, Kingsley Coman if fit, Anthony Martial, Ousmane Dembele, Kylian Mbappe, Dimitri Payet and Florian Thauvin), it seems that a 4-2-3-1 or 4-3-3 formation is much more suited to his squad. Will Didier Deschamps change his mind? -- Julien Laurens

BELGIUM: Can they beat the best?

This might be the last chance for Belgium's "golden generation" to prove themselves at a World Cup. They start among the favourites, with the caveat that we have seen this before: Despite showing promise, they fell short in Brazil 2014 and at Euro 2016, and it has become tempting to label them "flat-track bullies," who flop after sailing through the qualifiers.

But they have arguably the world's best player this season in Kevin De Bruyne and two forwards -- Romelu Lukaku and Dries Mertens -- who are greatly improved. If manager Roberto Martinez can achieve cohesion and underline his own credentials at this level, then this could be their time. -- Nick Ames

PORTUGAL: Can Silva help Ronaldo?

Bernardo Silva has finally hit his stride at Manchester City, and that can only be good news for Portugal. A winning goal against Chelsea on Sunday was the latest of several important contributions since Christmas, and his burgeoning confidence suggests he could play the kind of starring role his country needs.

While there will be focus on Cristiano Ronaldo and the fact that, at 33, this is effectively his last shot at winning a World Cup, he will not be able do it on his own, and Silva represents the kind of world-class assistance he has long lacked. -- Nick Ames

RUSSIA: Who will play in central defence?

With stalwarts Sergei Ignashevich and Vasily Berezutsky having retired after Euro 2016, coach Stanislav Cherchesov has had to rebuild his backline. He changed his system to three central defenders, using Georgi Dzhikia, Viktor Vasin and Fyodor Kudryashov together at the Confederations Cup. While the results might not have been outstanding, progress was evident.

But Dzhikia and Vasin both injured knee ligaments at the beginning of 2018, ruling them out of the World Cup and leaving Cherchesov in a bind that was made worse on Wednesday when the 35-year-old Berezutsky twins, Vasily and Alexei, ruled out a comeback. -- Michael Yokhin

ARGENTINA: Can defensive problems be fixed?

With Lionel Messi & Co. up front, Argentina should guarantee moments of attacking brilliance in Russia. But can they defend? Their last match, a 4-2 defeat by Nigeria, highlighted the problems.

Coach Jorge Sampaoli wants his team to squeeze play in the opponents' half, but his midfield is not pressing with intensity and, lacking pace, his back three drop deep. And without good full- and wing-backs, Argentina's wingers are expected to run 80 yards and defend. Sampaoli has little time to put things right. -- Tim Vickery

MEXICO: Will Europe-based players find minutes (and form)?

The fear in a World Cup year for many managers is that players are jaded at the end of grueling seasons, but with Mexico, Juan Carlos Osorio has the opposite problem. It looks as though several Europe-based players will be fresh, but out of rhythm and match practice.

Javier "Chicharito" Hernandez, Diego Reyes, Raul Jimenez, Carlos Salcedo, Marco Fabian and Hector Moreno have found playing time hard to come by of late. Mexico doesn't have the talent depth of the favourites, and the concern is that players will arrive for pre-tournament friendlies needing minutes to find rhythm and match fitness, rather than using them to refine tactical issues. -- Tom Marshall

AUSTRALIA: How will the lineup look under Van Marwijk?

With Bert van Marwijk new to the job, it remains to be seen the approach he will take after having replaced Ange Postecoglou. Van Marwijk has not yet managed in a game scenario, so whether or not he adopts the same 3-2-4-1 formation and cavalier attitude of his predecessor is unknown.

It seems likely, though, that he will look to incorporate some fresh faces -- Andrew Nabbout, Dimi Petratos and Aleksandar Susnjar have all been included in Van Marwijk's preliminary squad to face Norway and Colombia at the end of March. -- Rob Brooks

Africa: Might off-field issues affect performance?

There is a feeling that the World Cup is there for the taking. All five African qualifiers have strong squads, and some traditional teams don't quite carry the same fear factor. What look like difficult draws on paper could -- with a bit of luck -- prove to be more even.

And don't expect the headlines from Russia to be about bonus rows this time. Not only has FIFA taken proactive steps to ensure players are paid before the tournament, but Nigeria have led the way by signing agreements with players ahead of schedule. Egypt are in the process of doing the same, and it is excepted that Morocco, Senegal and Tunisia will follow suit. -- Colin Udoh

Asia: Is Saudi Arabia's Spanish plan backfiring?

One relative weakness of Saudi Arabia is that their players have competed at home. The federation made moves to remedy that in January by sending nine, including four internationals, on loan to Spanish clubs.

However, none of them has yet played, leaving fans to wonder if this is too little, much too late. The stars might benefit from training in Spain, but if the situation does not change -- and few think it will -- then a number of players on the Saudi squad will go to Russia having not played any competitive football in 2018. -- John Duerden