A long description of the off-side rule will tell you a player needs 2 players between the player and the goal when the ball is last played, if he is to be on-side. It this game there was no “second to last defender” as the Law book wants. There was one Pienaar against 2 Mexicans. If you replay the game observe this:
The goalkeeper comes out leaving Pienaar at goals. Then the ball touches a player and goes to Carlos Vela. Note that Vela and the corner kick taker are nearer the goal than all else except for Pienaar.
There is no offside from Corner Kicks until the ball touches the second player. A goal can be scored direct from a corner kick irrespective of anyone’s position. Once the ball touches a player – referee and assistant referee included, the right to score is lost, if the conditions above are not met.