Going out of order here, just because my notes for the Brazil/Mexico game are more accessible than those for the Belgium and Algeria (and there's more of them).
As expected, Brazil controlled the play through long stretches of the game. There were several times when, for a couple of minutes, Brazil would bring it down, get to the box, and Mexico would clear the ball. But Mexico did it by pulling so many people back that the Lusos would instantly return the ball to right outside the box and starting again.
It did help that, especially in the first, the foul calling seemed very uneven. It felt like anything close was a foul by Mexico, while Brazil practically needed to pull a (red! I know what El Tri means, but it's the first time I've seen them in red) jersey off the Mexican to get a foul. I think, based on the way things went later in the game, that that wasn't deliberate, but it felt like it for a while.
Despite all that, Mexico did manage to get some close chances, but not many. Most of them were shots from outside the box that barely missed the goal.
But the story of the game was definitely Guillermo Ochoa. Although he did have a clean sheet against Cameroon, I don't remember him making any great saves. Well, he made a number of them in this game.
First, he stopped a Naymar header from in close in the twenty-fifth minute. It was at the edge of the goal, down low, and, leaping at full extension, he got a hand on it and pushed it out before it could fully cross the line (it was more than halfway there, according to the goal camera).
In the 43rd minute, he had another great save; the defense tried to put the offside trap on, but Maza Rodriguez didn't get it, and left two attackers with no one closer to the goal (one was David Luiz, but I missed the guy who actually struck the ball), and Ochoa somehow made the save.
Much later, Thiago (who, incidentally, was the one who chested the ball through on the earlier failed offside trap) had an undefended header, off a Naymar free kick, from five yards out. Stopped, and the defense deflected the shot off the rebound.
He had another stop off a Naymar kick from about ten yards out.
Basically, without him, and some luck, Brazil would win this game, going away. But with him, they were mostly competitive.
But Mexico couldn't cash in on any of their chances either, and the game ended in a scoreless draw (second of the tournament, both in being a draw, and in being scoreless).
The draw put both teams in a good position to move on, although interestingly, it didn't guarantee either. In fact, if Croatia and Cameroon draw today, it's theoretically possible for both teams to be eliminated (the C's would need to win their last games by at least two; maybe even three). Very, very unlikely, but possible.