The first two questions are, "Have you done this kind of photography before using film and have you been more successful with film than with your digital?"
In the old high school and college days we used to push Tri-x to 1200, underexpose another third of a stop and shoot wide open with a f/stop of f/1.4 or f/ 1.8 to get a shutter speed of over 1/250th or use a flash (couldn't use the flash for conference games). There was grain to say the least and they were still underexposed, but the requirements for a newspaper shot were less strict.
Now with digital cameras (high quality, but not pro quality), you deal with cameras with f/stops of from 3.5 to 5.6 depending upon the focal length being used for the shot. That puts you down almost four or five stops at the start of your shoot. Using the same lighting in the first paragraph, that would mean you would have to shoot (without flash) at about ISO of 6400 and still be underexposed about a stop and a half. True, the lighting in the new sports complexes is more even and higher lux, but don’t expect tight grain and no “action” movement in your shots.
Take a look at the way the pros shoot at Basketball or Hockey games and you will see that they camp out at one end of the court (ice) and just wait for shots. Usually those areas are lit well enough to get flashless shots or in some cases (staff photographers can do this) use wireless remote speed lights pre-aimed and mounted up in the lights and used to capture the action.