Group C might be the most open group out of all of them, for a variety of different factors. Injuries, teams that have either major flaws or flawed big stage reputations, and the fact that they all have to play each other. Therefore, it might be the most fun to watch out of all of the groups in the tournament.
It has been 16 years since Colombia made the World Cup, and their arrival back on the scene is most welcome. It may be even more so if one Falcao was healthy, but his health has become the question that has no answer and whose answer might determine the fate of a group and 4 or 5 teams. The indications I've gotten from people is that he isn't healthy enough to play, but that may change by the time the games kick. Even if Falcao cannot play, Colombia are not a group of scrubs lifted by one player. They have quality up front with players like Teo Gutierrez, Jackson Martinez, and Adrian Ramos, and in the midfield they have quality such as James Rodriguez, Fredy Guarin and Juan Cuadrado. They will be able to create and score goals with or without the Monaco hitman. But losing him is going to create ripple effects throughout the group no doubt, since his presence lifts Colombia from being a solid team with a possible knockout stage pedigree to one that can not only win their group, but one that can make a deep run. Their issues come in the back, where a 38 old Mario Yepes will anchor the backline, and that should be a concern. One player to keep an eye on if he does play is River's young anchor Eder Alvarez Balanta, who probably will earn a European move soon. Does this team have shades of the Colombia squad of 1994? Possibly, but no one has El Pibe's hair.
The Ivory Coast. Always a bit of a tournament darling; always expected to do far better than they actually do, and such have been overtaken as the best African team by Ghana. Obviously though, they still have loads of talent everywhere, and you will know the names by now. For Sabri Lamouchi's men, it's a matter of putting it all together for the first time at a World Cup. They should be solid enough on the backline, they have the Premier League's best player in Yaya Toure, and up front they have not only an in form Gervinho (I did just type this) and Wilfried Bony, but they still have a guy named Drogba that might still be pretty good. This might be the final World Cup for this core of players, so there should be no excuses as to why they cannot get out of the group stage on their 3rd attempt at a World Cup.
Greece have long held a reputation of being defensively stout, but offensively lacking. That reputation is changing, but not at a rapid rate under Fernando Santos. While he's tried to bring a more open style of play to a nation that is accustomed to rock solid defending and nicking the odd goal, Greece's reputation has got the better of them at points, especially in qualifying when they allowed a grand total of 4 goals. They did score 4 in the playoff 2 legs against Romania for the record. They are a team in transition from the generation that helped them shock the world and win the Euros 10 years ago to a younger one that hasn't quite matured yet, which means this World Cup could be in an awkward time for the Greeks. If they want to get out of this difficult group, they will need to hope that Kostas Mitroglou shakes off his disastrous form from his Fulham time and finds his pre-move form when he couldn't stop scoring, or that Georgios Samaras does what he has done in past big games. Maybe defense will be the best in this group with potent attacking threats, but it remains to be seen whether Santos can impose his new style or whether the old Greek ways will come on strong.
Japan are Greece's polar opposite team. Technically gifted like almost no other team in the tournament, and they have all of the attacking talent one could ever want, meaning that for neutrals they may be the most fun team to watch. However, they have major deficiencies at the back, partially from style and partially from development. And Eiji Kawashima is prone to the odd gaffe every now and again... of the major variety. But they should be able to score in big gulps against everyone, as evidenced by the Confederations Cup performance against Italy when they scored 3, but allowed 4. Whether that formula will be good enough to get them out of a group with Colombia and the Ivory Coast in it remains to be seen.
Prediction: It depends on the health of Falcao. If he's good to go, then Colombia are the odds-on favorites. I If not, anyone can win this group, and I mean anyone.