Thanks Isac. It's a big improvement, so thanks heaps.
There was actually a ball, blurring its way past the other girl in red (it's soccer, by the way).
One more thing. Sorry to be cheeky, but would it be possible to isolate the girl, i.e. remove the background, so that I can superimpose her onto a different background for a graphic idea?
Also thanks for the suggestion re-shutter speed. I am very new to this and just have the settings the camera store guy recommended. I am using a Canon EF 70-200mm 1:2.8 L IS II USM lens, and I know I should be getting much better clarity than I do. You are right, the shutter speed was 1/125th, so I have upped that to 1/1000. It is also on F5.6 and ISO Auto, so any other suggestions you have would be greatly appreciated. My shots are even worse for night games under floodlights.