probably vs Randleman in mma, coulda been vs Alberto del Rio though. I'm sure I saw him in k1 before that though.
His MMA debut against Fujita 
Cro Cop vs Dos Caras Jr(Alberto Del Rio). 
PRIDE 20 v Wandy
His K-1 loss to Michael McDonald then the mixed rules fight with Wanderlei in Pride
I'm not sure.
AlphaMaleJP - Cro Cop vs Dos Caras Jr(Alberto Del Rio).Me too
Dos caras haha. God pride was such a spectacle
Ended via head kick. Surprise
I'd read a lot about him but didn't see any fights until his K-1 match against Bonjasky in 2002. This was screened on Eurosport shortly after the event.
MMA - Due to lack of TV coverage in UK and very shitty dial-up I only caught fight highlights until his UFC debut against Eddie Sanchez in 2007.
vs Bob Sapp
Instantly Hooked!
vs Sakuraba and I thought he was a dirty prick
I eventually warmed up to him though and in fact am a huge fan but still cant deny the horrible tactics in that fight
Sadly, it was his first fight with Gonzaga :(
I remember thinking how brutal that looked, the way his leg twisted, and people saying that Gonzaga "Cro Copped Cro Cop". Didn't know what that meant, so I looked into it.
First fight I saw of his in Pride was Igor. Became an instant fan and wish I could have seen those Pride fights live as they happened.