What to say about games in knockout phase but only that everything is possible, there is no mistake and games will be completely different from the group stage.
In first game Argentina will play against France, and whoever is watching Argentina games may think France is has a greater chance to win. In first game Argentina is play draw with Iceland and this was a surprise, but then they are literally shattered by Croatia in second game. Even Nigeria was an almost impossible mission for them, they are in this phase just by luck, nothing else. But usually teams who play bad in group stage start to play much better in knockout phase, it is possible that Argentina finally play good football against France.
Way to the final is looks like this :

Japan joining the top 16 is an upset yet it would be hard for them to advance. But my bet will be Japan beating Belgium in this round. What do you guys think? Would it be the smaller Japanese beating the bigger belgians?