Second line advice here........(I'm not nearly on the level with some of thise people who have already offered you some advice.) If Tuesday comes and he can't play his best, does he call and explain and say I'll wait until next audition rather than play poorly, do you show up and explain followed by a hand shake, or do you play with the chance of playing a bad audition? In the past (many years ago) I had a fever blister so bad it was bleeding. I showed up, explained why I could not play for them, shook hands and thanked them for the time they had reserved for me. I also offered to play if they really wanted me to do so, but told them I would rather not play until my lip was totally better. I got a call about a month later to do some work for the same guy. I showed up and played the heck out of the job and showed them my "real stuff". I know I could not have done that when my lip was messed up. I never want to pick up a horn and play bad -- it leaves an impression that is very hard for a person to ever forget.