You are probably going to want to shoot manual. Here is a shot taken at an indoor stadium. I was using an EX500 flash. I had to shoot at 800 ISO in order to get an acceptable exposure with my shutter set at 1/80 and obviously you want your aperture open to help out. I was at f5.
Not familiar with the S2 but I do use IS lenses and image stabilization is not going to help at all concerning freezing motion of the subject. Your built in flash is not going to help much at long distances either.
Start with a 100 ISO on manual with the aperture wide open (small f number) and see what shutter speeds you are getting and then bump the ISO up until you get an acceptable shutter speed.
If you are going to be shooting still subjects such as players in stance then the IS will help and you might be able to drop the ISO a bit for a clearer pictures or close the aperture a bit for more DOF and sharpness.