X-factors for each 2018 Men's World Cup team

Need more than Messi. So close in 2014, the reigning World Cup runner-up looked far from potent during qualifying and needed one of the game's greats to get to Russia. Lionel Messi, who has five World Cup goals and 21 in qualifying, is enough to keep Argentina a contender, but if the likes of Nicolas Otamendi and Sergio Aguero step up, it's unfinished business could be settled.

Bert van Marwijk. The Socceroos are a long shot to even win a match in Russia, but van Marwijk's presence is intriguing nonetheless. Named coach in January after guiding Saudi Arabia to World Cup qualification, van Marwijk fell short of the title with the Netherlands in 2010. He won't have much time to whip the Aussies into shape before leaving this post after the tournament.

Roberto Martinez. With Kevin De Bruyne, Romelu Lukaku and Eden Hazard, for starters, the Belgians are loaded. The key will be how Martinez, in his first international managerial gig, handles that talent and gets it to work in his system. Belgium is again a team worthy of making a serious run, but is this a case of having too much talent?

Overconfidence. Following a disappointing fourth-place finish as World Cup host in 2014, Brazil is again considered a favorite with Germany and Spain. Led by the charismatic Neymar, the five-time champs are stacked with talent. They know it, and sometimes their knack for flair over substance can be a detriment.

Memories of 2014. James Rodriguez's coming-out party in Brazil four years ago helped Colombia reach the quarterfinals for the first time, and that thirst for success has not subsided. With Rodriguez and Radamel Falcao leading the way, Colombia might have the talent to take the next step. Like Argentina, qualifying was a chore, but the Colombians have regrouped with some solid play leading up to the World Cup.

Keylor Navas. The Real Madrid goalkeeper is well-known on and off the pitch, but he'll need to stand on his head if Costa Rica is to even win a match in the group stage. The Costa Ricans scored one goal in four matches heading into June, so Navas must keep his team in games and hope for some offense to show up.

Magnificent midfield. Ivan Rakitic, Luka Modric and Ivan Perisic make up perhaps the best midfield in the world, but the truth is that Croatia has not made it out of the group stage in its last three World Cup appearances. Yet, with the talent, it's easy to see why this nation is a perennial darkhorse for such competitions.

Christian Eriksen. The Tottenham product practically got Denmark through qualifying on his own and is sure to draw plenty of attention from World Cup opponents. If Eriksen is able to maintain his recent international success and strong playmaking skills, then the Danes could reach the knockout round for the first time since 2002. 

Salah the stupendous. Egypt's chances begin and end with Liverpool star Mohamed Salah, who has recorded more than 40 goals over all competitions this season. Aside from Salah, who is in for a big club payday next season, Egypt doesn't offer much notable support, but with Russia and Saudi Arabia in the group, the Egyptians have a decent chance to advance along with Uruguay.

History. Exactly what point will the hearts of Three Lions fans be shattered? If the past is any indication, it will come sooner than their faithful hope, despite again boasting some of the world's best talent like Harry Kane and Raheem Sterling. Memories of the 1966 title remain precious because England hasn't advanced past the quarterfinals since 1990 and didn't get out of group play in Brazil.

Defense. With 18 goals from 10 qualifying matches, France proved it's very capable of finding the back of the net. However, if they are to contend with Germany, Spain and Brazil, defending will be key. The French yielded just one goal in their final four qualification matches, but the loss of veteran defender Laurent Koscielny to injury is a big blow.

Die Mannschaft. Translated, it means "The Team." That's how the defending champs play: together, in every facet. The Germans went 10-0 in qualification and have a budding star in 22-year-old Timo Werner. Expectations are high, but the overall level of talent on this side may be even higher.

Passion. Backed by its exuberant, thunder-clapping fans, Iceland is ready to take the World Cup by storm in its debut — or, at least, make it out of Group D, which is not impossible even with Argentina and Croatia in the way. Iceland's improbable run to the Euro quarterfinals in 2016 showed it's not the size of the nation but the heart and will of the players that sometime prevail.

Sardar Azmoun. Iran has never made it past the group stage in four World Cup trips, and that drought likely will continue while drawn in with Portugal and Spain. The 23-year-old Azmoun, however, has 11 goals in World Cup qualification so at least Iran has a budding star capable of disrupting the natural order.

Lack of cohesion. That's usually what happens when a managerial switch is made two months prior to the event. Former Japanese Olympic coach Akira Nishino took over last month for fired coach Vahid Halilhodzic, who reportedly lost the trust of his players. It will be a tall order for Nishino to bring this group together and get out of the group stage.

Taking the next step. For all its rich history of the sport and national celebration of the game, El Tri has made it as far as the World Cup quarterfinals only twice. Talented enough to consistently compete with the best in the word, Mexico should again advance past the group stage. That's where things have stalled, and by all accounts, this year's group might keep that trend alive.

Scoring. After allowing just two goals throughout World Cup qualification, there is no doubt Morocco wants to dictate the pace of play through its defense. However, it scored more than two goals twice and was shut out four times during those qualifying contests.

Argentina. With Messi and Co. no sure thing, Nigeria might have its best chance to finally take down the two-time champs. Nigeria has been in the same group with Argentina in all but one of its previous five World Cups and suffered one-goal losses in all four meetings. They'll meet again in Russia, but this matchup brings even more importance with Croatia and upstart Iceland also in Group D.

Anything is possible. Sure, the Panamanians will be primed for their World Cup debut, but in the end they'll likely just be happy to be there. This a team that lost 4-0 to the United States, which, in case you haven't heard, did not qualify for this event

Paolo Guerrero. Peru's chance for success in Russia hinges on the status of its captain and national football treasure. Guerrero's one-year ban for testing positive for cocaine metabolites was trimmed to six months. However, the World Anti-Doping Agency has appealed the reduction, which again leaves Guerrero's World Cup status uncertain.

Can it hang with the big boys? Poland suffered just one loss in qualifying, but that was 4-0 to a Denmark team that's similar because it can beat the teams it should but not the ones that matter. Robert Lewandowski is world-class, but recent friendly losses to Mexico and Nigeria leave Poland as nothing more than a potential sleeper.

Replicate Euro '16. While the presence of Cristiano Ronaldo — and his abs — always gives Portugal a chance for a deep run, that Euro title proves it's really capable of being the last team standing in a major competition. The Silvas, Andre and Bernardo complement Ronaldo on a team that still remains a World Cup mystery.

Home-field advantage. It's been 20 years since a host nation (France) won the World Cup. Nobody is giving the Russians any chance to be the first team to do it again, but after Group A favorite Uruguay, Egypt and Saudi Arabia are beatable opponents for a nation that's mediocre at best.

Nowhere but up. Saudi Arabia is the lowest-ranked team in the World Cup field, and its only tournament victories came in 1994. The good news is that first-match opponent Russia ranks just above the Saudis. Mohammad al-Sahlawi is a talented striker, but that's about it.

The back end. While Sadio Mane and Keita Balde can do the job up front, Senegal's unheralded defense is likely what gives it a chance to reach the knockout round. The national team allowed three goals in its final seven World Cup qualifying matches.

Mladen Krstajic. He replaced Slavoljub Muslin as manager and was given the permanent job before the new year. Krstajic has a roster filled with some solid young talent, but whether things come together in Russia under his watch remains to be seen. Setting their sights for big things in 2022 might make more sense.

Health. The injuries continue to pile up for South Korea, which is making its ninth straight World Cup appearance. It's uncertain if defenders Kim Min-jae and Kim Jin-su will be available for the World Cup, while captain Yeom Ki-hun reportedly will miss four weeks with a rib injury. 

Redemption. No team has more to prove in Russia than Spain. The 2010 World Cup champions failed to make it out of the group stage in Brazil, and the sting won't subside until the Spanish prove it was a fluke. One of the overall favorites, Spain has the perfect blend of experience (Sergio Ramos) and youth (Alvaro Morata) and maybe the tournament's best keeper (David De Gea).

Slayer of giants. En route to qualifying for its first World Cup since 2006, Sweden knocked off France and was the reason Italy shockingly failed to qualify. Then it edged Portugal in a March friendly. Even without Zlatan Ibrahimovic, the Swedes won't be intimated by Germany and Mexico in group play.

Sneaky confidence. The Swiss lost only one match during qualification, to Portugal, and also have looked good in recent friendlies. Making a fourth straight World Cup appearance, Switzerland has reached the knockout round twice in the last three World Cups, and that trend is expected to continue as it chases Brazil in Group E.

Preparation. In the same group as Belgium and England, Tunisia faces a tall order in Russia. However, it enters with March wins over fellow World Cup teams Iran and Costa Rica, and by the time the tournament opens, Tunisia will have faced Portugal and Spain in tune-ups. 

Depth. Luis Suarez and Edinson Cavani are still two of the best in the world, but where does Uruguay go from there? That pair should help win Group A, seemingly without much trouble. However, it's uncertain who else will step up to help Uruguay advance past the round of 16.