Each sport has its own unique attributes and requires different skills, equipment and knowledge of the game from the photographer.

AFL and Rugby have been some of my favourite, each with their own dramatic moments;

In rugby, the positive aspects are:

• players largely advance forwards 'in a line' due to the offside rule
• players are coming towards you, thus providing a better chance of getting 'two faces and a ball' in the shot
• dramatic celebrations after the 'battle'

whereas the challenges are:

• players drop their faces towards the ground just before making contact. Thus, unless you're really low to the ground, you'll get a lot of the top of players' heads
• as the attacking and defensive lines face each other almost 1-on-1 in a line drifting in the direction of play, you'll get many players crossing between you and the player you're shooting
• many movements are short bursts of only a few paces which produce 'static' looking images
• you'll mostly get the faces of either the attackers or defenders from behind goal area - not both. To get both you need to move to the sidelines and take your chances with medical staff, TV crew, linesman, balls boys etc between you and the play

In AFL (Aussie Rules), the positive aspects are:

• players are often jumping up towards the ball in the air exposing their faces
• game is played at high speed producing a sense of urgency, concentration and speed in the images

whereas the challenges are:

• players run in 'random directions' on the field twisting and turning all the time as defenders can come from any direction making it difficult to get faces or clean shots
• the size of the oval (officially 135m x 165m! - almost 2 rugby fields side by side with an elliptical border) - try shooting that with a smartphone! 
• no offsides rule, so the play moves very quickly towards and away from the photographer

But they're all fun to shoot and it's a great feeling when you 'know' you've got THAT shot, even before you get home to view them on the computer