The 35 prime is a popular lens, but as you're more of a zoom guy I'd suggest the 24-70. As you know, it uses fairy dust to power the motor, something which a prime won't match. You have all bases covered. Get the bread and butter shots in round one along with the bulk of your set then change lenses at the break, 18-35 for a bit, 70-200 for a bit, mix it up, shoot through stuff, ropes, boards, people, get the crowd (if there is one) cheering, corner staff, ref, ring girls etc, shoot into any lights, get some good flare etc etc. Almost makes me want to do it again... almost.
Have fun.