Stadium lights as well as indoor sports facility lights can cause your DLSR's auto white balance setting to produce colors that just aren't correct. Although you can use a test target like a gray card, there's a product called Expo Disc that I now use to easily set white balance in strange lighting conditions. The Expo Disc attaches directly to the lens to allow you to obtain a white balance measurement and obtain an incident reading.
Before the photo above was taken under high school stadium lights, I used Expo Disc to easily get a proper white balance setting on my Nikon D300.
