Our expert bloggers will give their thoughts ahead of each game, so as Argentina take on Iran in Group F, Sam Kelly (Argentina) and Afshin Afshar (Iran) are your guides.
What's at stake?
Sam Kelly: Off-field political talk aside, there's not much in a footballing sense between these nations. They've met just once, in 1977 during a friendly competition that celebrated Real Madrid's 75th anniversary. That match ended in a 1-1 draw in the Bernabeu. Of course, regardless of the opposition, Argentina have one big prize in play here -- if they win, and the match between Bosnia-Herzegovina and Nigeria ends all square, Argentina will have topped the group with a game to spare.
Afshin Afshar: Argentina and Iran's head-to-head history is limited to a friendly in Madrid's Santiago Bernabeu Stadium in 1977. The two sides reached the semifinals of the four-team tournament and tied 1-1 in regular time, with Argentina prevailing in the ensuing penalty shootout.
Not many experts give Team Melli much of a chance against Albiceleste. As a matter of fact, most Iranian fans have already written this match off as a loss; however, not all will be lost in case of a defeat. Team Melli will still be in the hunt for the second spot going into the final round of the group stage. However, they must not let in too many goals from the fearsome Argentine offense. The Team Melli players and their coaching staff are motivated to show the world that they are not the pushovers everyone forecast prior to the tournament.
SK: I'll be keeping an eye on Fernando Gago in this one. His introduction at halftime of the opening 2-1 victory over Bosnia-Herzegovina was as important to Argentina's second-half improvement as Gonzalo Higuain's entrance, and both will be playing from the start here as coach Alejandro Sabella moves back to his first choice 4-3-3 system.
To that end, Gago's role in knitting together passes in the midfield and threading them through (Yes, that pun is intentional. No, I'm not proud of myself.) to Lionel Messi ahead of him will play a huge part in whether Argentina can put in a more convincing performance the second time. Even more so since, having seen Iran's 0-0 draw with Nigeria, it's probably safe to assume they'll be defending in numbers again.
AA: Assuming that Iran coach Carlos Queiroz will field the same starting 11 that he used against Nigeria, the precarious task of defending the world's best player in Messi will fall mostly on defender Mehrdad Pooladi. The 27-year-old Persepolis FC defender's six tackles, a header off the line, and five completed passes in six attempts on Nigeria's side of the field earned him a 9.7 index score that placed him second only behind Thomas Muller of Germany in FIFA's top 10 list at the end of the first round of matches. Pooladi will be a busy man trying to keep up with "La Pulga," but he has never been one to be intimidated. His performance on the left side of Team Melli's defence will be a key factor in this match.
SK: Amir Hossein Sadeghi was important for Iran's game plan in the first match, and could become even more so in this one. The 0-0 draw against Nigeria was possibly the dullest match of the tournament so far, but on a tactical level Iran did pretty well what they'd set out to do: defend deep, block Nigerian attacks off and seek to play the ball out from the back rapidly on the few occasions they got a chance to counterattack. Sadeghi's passing was key to that -- 94 percent pass completion is an impressive stat, particularly for a side that ceded much of the possession. Against Argentina, they will of course again be going out expecting the opposition to take the game to them, and they will have to make the most of any respite they get from Argentina's attack. Sadeghi will have to put in a good performance if Iran are to make things count when they have the ball.
AA: Messi, Sergio Aguero, Angel di Maria, Higuain, and the list goes on. Argentina is loaded with proven offensive talent, but if there is one player to be feared, it would be Messi. The FC Barcelona superstar is eager to prove himself on the world stage, and he will be ready. His skill, pace and vision is nothing like Team Melli defenders have ever experienced. He will be the one leading the onslaught Saturday.
SK: Khosro Heydari vs. Marcos Rojo. Heydari covered more ground than anyone else on the pitch against Nigeria, and from his position on the right of the Iranian midfield, he's ideally placed to test Rojo, Argentina's weakest player ("rabona" clearances from inside his own penalty area notwithstanding). To that end, how well Heydari (and Iran right back Pejman Montazeri) track di Maria's runs from the left side of Argentina's midfield three will also be important. If Heydari gets the chances to run at Rojo and takes those chances well, he could be key to Iran's chances of pulling off a shock.
AA: The above-mentioned Messi vs. Pooladi matchup aside, the di Maria vs. Heydari battle should also play a great role in the outcome of the match. Heydari covered a whopping 11.5 kilometres against Nigeria, linked well with Montazeri, and spent about 65 percent of his time in his own half defending against Nigerian exertions. Look for him to closely track di Maria every time the speedy Argentine makes his runs up the field. Should Heydari manage to keep di Maria in check, Argentina's front line will be getting fewer quality passes.
SK: Argentina should be much better than in the disjointed first half against Bosnia-Herzegovina on Sunday, and should click here with a full strength starting XI. They've also not had to travel for this game -- it's being played in Belo Horizonte, where their training camp is. They're favourites for a reason, and should be able to win this 3-0.
AA: Still on a high from their well-organized defensive performance against Nigeria that produced Iran's first World Cup clean sheet, Team Melli will go into the match against Argentina with more poise. However, it is hard to imagine that they can repel all of Argentina's attacks. Argentina to win 2-0.