An ageing squad and hosts Brazil are Spain's biggest troublesome areas and overcoming these two factors will decide if the Spaniards can become the third country after Italy and Brazil to retain their World Cup crown.
Spain, however, have been off the boil for some time. They were completely outclassed by hosts Brazil in the final of the 2013 FIFA Confederations Cup and lost to minnows like South Africa in international friendlies.
Their narrow, lacklustre victories over sides like Belarus and Equatorial Guinea showed they were not the side that took the world by storm in the Euro 2008, World Cup 2010 and the Euro 2012, making them the only national team with three consecutive wins of either the continental championship or the World Cup.
With the likes of Neymar, Oscar and Willian in the side, few would bet against Brazil topping Group A and going a long way into the tournament.
Playing at home will also play a major role with six countries lifting the title when they have hosted the tournament.
Brazil also comes into football's showpiece event with some momentum behind them after winning the FIFA Confederations Cup. They outclassed defending World and Euro champions Spain 3-0 in the final.
However, protests in the country and the team being booed in their final warm-up game will have a negative effect on the host nation.
Messi and Co. have somehow kept themselves away from the limelight and that is a good thing for a team increasingly looking like tournament favourites. Messi scored in Argentina's final warm-up game and the team seemed to be gelling well.
With the World Cup happening in their backyard, the Argentine players will be licking their lips having to play in familiar conditions.
Four years ago in South Africa, Diego Maradona was at the helm of the team and his boisterous and attention grabbing attitude only had an adverse effect on the team.
Messi's poor form and injury struggles for his club Barcelona this season has also lifted some weight of the diminutive forward's shoulders.
With few talking about Argentina as tournament favourites this is when the white and blue stripes will be at their most dangerous.
Not France, not England, not the Netherlands -- Europe's best chance, barring the ever-reliable Germany, of winning the crown could be dark horses Belgium.
Belgium qualified for the World Cup in an emphatic fashion by recording a national record of seven successive wins during an unbeaten campaign.
They won eight matches out of 10 and drew two to top the qualification group. The team gave a series of controlled and powerful displays throughout the qualifying, where their defence was extremely disciplined.
If Portugal have Cristiano Ronaldo, Argentina have Messi, Brazil have Neymar, the Belgians have probably the best young player in the team -- Eden Hazard.
A technically sound playmaker, the 23-year-old can explode at any time during a match by generating sudden pace and energy.
His trickery down the wings for English club Chelsea this season gave many a defenders nightmares. If on song, the youngster will be very difficult to stop and could take his team to their best ever finish at the WOrld Cup.
Manchester United's Marouane Fellaini and Manchester City's Vincent Kompany are two players who are also expected to come good for Belgium.
However, Wilmots has expressed concern that there might be a problem with a number of players like Thomas Vermaelen, Kevin De Bruyne, Nacer Chadli and Romelu Lukaku not having much playing time at club level.
A renowned player during his time, Marc Wilmots became coach of the Belgians two years ago with the aim of guiding them to a new high and the coach accomplished it in style when the country achieved its best ranking of fifth from 54th.
Their best finish at the mega event was fourth in 1986. However, they failed to qualify in the last two editions in Germany and South Africa.