I was there too! It was a very hot August night! Ozzy had just played at Deer Creek, Indiana the night before. This was my first real rock concert! I remember the arena dark during the intro music, then Ozzy's image could be seen behind the giant curtain, all big and illuminated. I can still see Mike Inez during that moment with his bass waiting for the curtain to drop. Hey! It was quite a moment! Many moments during that show!
kevin, thanks your comment/update was correct. i've deleted my entry. ("I attended this concert but it wasn't at Riverfront Coliseum nor was it in 1991. This concert was at Cincinnati Gardens on August 20, 1992. ")