On the photo you can see the muscle work (photo: A. Pratzner)
Sports photography is characterized by fast movements - sometimes extremly fast movements.
That is why you need to know the sport and best the players to know the moment they will do the important sports stuff. Like taking the shot on a football goal you need to capture that moment and for that you best should know when that moment will happen. Or jumping up to dunk a basketball. If you know when and where it will happen - then you can adjust and photograph it. Still it is a fraction of a second so you need to train it before and know your camera and its settings.
Additionaly you as a photographer often have to fight bad light situations, which often occur in sport facilitites or while football games which are spoiled by raining.
To compete with these adversities, you need several things:
2-4 players and a ball (mostly yellow). Tennis is charaterisied by fast movements and tactical play, to save your own strength, while making the enemy do mistakes by exhausting him. Or simply play so overwhelming that you win.
Tennis ball dormant (photo: A. Pratzner)
The picture above was shot with an exposure of 1/1000 seconds. This wasn't necessary - however, the picture got taken in a break between 2 motion studies (and the camera was still set like that).
Tennis can be a game with high speeds. The ball can have after an serve up to 240 km/h (serve of Andy Roddick from the USA).
A fast serve is half the game (photo: A. Pratzner)
And when looking at some picture you can think about, where the photographer has been when he made the picture - as you can see in the following picture.
Total dedication (also from the photographer) (photo: A. Pratzner)
In the last picture you can nicely see motion blur of the tennis player through the fast movement. If I would have taken the shot with a higher exposure (so above 1/1600 seconds) the motion blur would have vanished. The Ball is depicted nearly sharp.
Very interesting are the sequences of an incident - that is the reason why serial pictures are a clever idea. Keep your finger on the trigger (lateron you have plenty of time to delete the bad ones).
For good pictures the photographer should permanently sit in ambush and move the camera with the events that occur. Often it is about capturing emotions.
Football and "a foot in the way" happens quite often (photo: A. Pratzner)
When Gravity is against you (photo: A. Pratzner)
Friendly matches need conciliatory gestures (photo: A. Pratzner)