Keeping up with Argentina
At first glance Group F looks like a one-horse race with Lionel Messi leading Argentina and a competitive challenge for second.
Argentina have by far the best pedigree with Messi, Gonzalo Higuain, Sergio Aguero and Angel di Maria forming one of the most feared attacks.
If anyone can challenge Brazil, it is surely their neighbours who have won the cup twice.
They dominated South American qualifying leading up to the Brazil tournament and Messi has now replaced Diego Maradona as his country's leading scorer.
Argentina's defence can let them down, the team have not reached the semi-finals since 1990, and World Cups have a habit of uncovering sudden pot-holes. But it would be a major surprise if Alejandro Sabella's team does not win Group F.
In their wake, the likes of Nigeria, Iran and debutants Bosnia can all realistically dream of making the knock-out stages.
Argentina's World Cups have a habit of uncovering sudden pot-holes, but it would be a major surprise if the twice former winners did not reach the last 16, most probably by winning their group.
In terms of ability and recent form, Bosnia would appear to be their prime challengers, boosted by the likes of Manchester City striker Edin Dzeko and Roma playmaker Miralem Pjanic.
But this is unchartered territory for the former Yugoslav republic who are competing in their first ever major championship.
However, they had been getting mighty close over the last few years, losing a two-legged play-off to Portugal for both the 2010 World Cup in South Africa and the 2012 Euros in Poland and Ukraine.
Now they have finally made it to a major tournament, Bosnia have the players to reach the knock-out stages.
However, the true question is whether or not they have the experience, confidence and cool heads needed to get a result against the Nigerians and Iran.
Nigeria are the most experienced of the trio having qualified for the World Cup all but once (in 2006) since making their bow in 1994 in the United States, where they helped eliminate Argentina in the pool stages before exiting in the last 16. That was their best ever performance alongside a similar showing in France four years later.
And coach Stephen Keshi has stamped his authority on a Nigerian squad long riven by personality clashes.
Iran must be viewed as the outsiders as in three previous appearances, they have never made it out of the group stages and have won only one out of nine matches.
Coach Carlos Queiroz has also turned to expatriates in European leagues.
Ashkan Dejagah last month suffered relegation from the English Premier League with Fulham.
Iranian-born but brought up in Germany, Dejagah won the German Bundesliga with VfL Wolfsburg in 2009.
The Iranian forward line also includes Reza Ghoochannejhad of Charlton Athletic in England, Alireza Jahanbakhsh of Dutch side NEC and Masoud Shojaei of Las Palmas in Spain.
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