To freeze motion, you need a fast shutter speed. As available light drops, you need longer shutter speed. They work against each other. You can turn the ISO setting up which will allow you to get by with a faster shutter speed in the low light. Fast glass is also important. For most folks without a big lens budget, that means putting the slow telephoto in the bag and using a shorter lens that is faster.

Here's how I'd approach it. Set your camera to shutter priority. Set your metering to be heavily center weighted. That way bright backgrounds won't interfere with metering. Crank your shutter speed to 1/500, ISO 800 and take some test shots. Play with ISO, but even a good camera will show some graininess at high ISO settings. If you need to go toward 1/1000 like Sneezy said. If your camera thinks it needs flash, even at the widest aperature, go to a faster lens.

If you can't get a fast enough shutter speed to remove the blur at your widest ap and ISO 800, position yourself so that the action is moving toward you. That way the motion will be mostly within the focal range of the lens, not moving across it. Doing this can get you a good picture of the ball carrier and the blockers/defenders in the general area, but the other players pursuing may still be blurry. Sometimes that's a good effect. If there are lights, set up so that the action might be moving toward you into the area near a light. That maximizes your opportunity to get a shot.

If you want to use a full auto mode, pick the one that looks like a runner. That will optimize for fast shutter speed. In any mode but full manual, keep the sky out of the frame until dark. All of the white background will make the camera think the scene is very well lit and it will slow/stop down.

Shoot RAW so you can up the exposure in Photoshop.