Our expert bloggers will give their thoughts ahead of each game, so as Mexico take on Cameroon in Group A, Andrea Canales (Mexico) and Salim Masoud Said (Cameroon) are your guides.
What's at stake?
Andrea Canales: Mexico and Cameroon have played against each other only once, a friendly match in 1993, which Mexico won by a single goal. Thus, there isn't a long and bitter rivalry, but it should still be a spirited encounter.
That's because both squads believe this match is the place to collect a full three points and start the path toward advancing from the group. Coaches will likely see their impact players emerge or revamp starters to find those with the will to affect a match.
Salim Said: With general acceptance by all parties that host Brazil will be the runaway Group A winners, this is the first of two Cup finals for Cameroon.
Drafted in the fortunate position of facing Mexico and Croatia in their opening two games, their target is simple: two games and two wins. Or at least a win and a draw. No losses -- unless they really fancy the near impossible task of toppling Brazil in front of their fans.
This game is their most winnable one, so gobbling up three points would be a huge, confidence-building result if they are serious about progressing to the knockout stages.
AC: Giovani dos Santos is coming off a fine season at Villarreal as a striker. Wily and creative around goal, he can have games where he hits another gear and is magic on the ball. Otherwise, he is not a classic striker and has to find a way to mesh better with his Mexico teammates.
Often used as an attacking midfielder, he sometimes drifts aimlessly in search of the ball or dribbles for too long instead of triggering chances on goal. However, if he can avoid these negative tendencies, he can make incisive plays for Mexico.
SS: Cameroon's Eric Maxim Choupo-Moting. With Mexico deploying a wing-back system, Choupo-Moting will have to maintain his defensive discipline perhaps even more than usual due to the uniqueness of the formation.
There should be plenty of space for the in-form winger to exploit on the flanks and run with typical fearlessness at a ponderous Mexico back three.
After Samuel Eto'o, he is the most clinical player in the team. Scoring goals was a problem during qualifying, and with Pierre Webo, who is likely to start on the bench, the only other attacker with a respectable international goal tally, Choupo-Moting will need to continue his impressive goal-scoring form and performances from the pre-tournament friendlies.
AC: Eto'o has scored 56 goals for Cameroon and cannot be overlooked. Age and experience have made him aware of every trick that exists to beguile defenders and score a goal.
Now that the financial dispute between the Cameroonian players and their federation has been resolved, as the captain of the squad, Eto'o may be more eager than ever to prove that Cameroon can finally advance out of the group stage for the first time since 1990. Otherwise, former Cameroon great Roger Milla's claim that Eto'o "still hasn't brought anything to our national team" won't ring so hollow.
SS: Oribe Peralta. His ruthlessness in front of goal could be decisive against a Cameroon defence that does have lapses in concentration that present the opposition with easy chances.
What's more, his aerial ability and hold-up play could pose problems for the defensive core of Joel Matip and Nicholas N'Koulou. With the aerially commanding Aurelien Chedjou probably not fit enough to start, there is a suspicion that Matip and N'Koulou are too like-for-like as a pairing. They are both lithe, ball-playing defenders who do their work cleanly and stylishly rather than relishing the hurly-burly of aerial and physical duels.
AC: Rafael Marquez and Eto'o is an especially intriguing matchup because both players were teammates at Barcelona for years. As Marquez is a defender and Eto'o a striker, they no doubt went hard at each other in countless training sessions, and may be aware of certain tendencies of the other's game that perhaps can still be exploited.
The two players certainly respect each other, but will not want to come out on the worse end of this rivalry, both for national and personal pride. Marquez will need to be careful of the speed of the Cameroonian, which is likely to surpass his own.
SS: Benjamin Moukandjo versus Miguel Layun. This game will be decided on the flanks. Cameroon's creativity will come from the wings and Mexico's two wing-backs, who push up very high, are the keys to their system.
I could have similarly picked Choupo-Moting vs. Pablo Aguilar on the left flank, but I have gone for Moukandjo vs. Layun because I believe Moukandjo is more tactically naive than Choupo-Moting. He will have to stick to his defensive duties, especially if the attack-minded Cedric Djeugoue is preferred over the more defensively sound Allan Nyom at right-back.
AC: Since their quarterfinal splash in 1990, Cameroon has won only one World Cup match, against Saudi Arabia in 2002. Mexico will be gunning for full points here, and even a draw will be considered a loss for a squad that regularly advances out of group play. Mexico 2, Cameroon 1.
SS: Some of Mexico's weaknesses can be exploited by an aggressive Cameroon midfield and pace on the flanks. I'm going for a narrow 2-1 win for the Indomitable Lions.