First, I am an amateur, so please have patience. Was puzzled by an incidence in the Man City-Chelsea game this Saturday. A long ball is hit to Anelka, who is 1 vs. 1 with the final defender. As Anelka runs into the box with possession of the ball, the defender bangs into him from behind (possibly intentionally, possibly not -- the field was very slippery), sending Anelka to the ground. Whistle is blown, PK is signalled, and a yellow card is given. To loud boos from the home crowd, which wanted a red card. OK, so I went to look this up in the rulebook. Found nothing about the last defender being a red card offense, although that must be somewhere (where?). However, The Laws of the Game say - "A player is sent off and shown the red card if he commits any of the following seven offences: 5. denies an obvious goalscoring opportunity to an opponent moving towards the player’s goal by an offence punishable by a free kick or a penalty kick" Huh? This does not indicate discretion on the part of the referee. And most certainly, this was an obviously goalscoring opportunity that was punished by a PK. So why only the yellow?