Definetly Calzaghe-Lacy, I couldn't believe that even happened. I remember I was a kid and I was watching RJJ-Toney, and they were hyping Toney up so much but it honestly looked like any other of Roy's fights. At the time I didn't know who Toney was so when I got older and found out I was amazed, as a kid I believed RJJ to be invincible after that.
there must be a lot of tyson fans on this board because no one has yet to mention: Lennox Lewis vs Mike Tyson! That was very one sided and the one sidedness continued for 8 rounds! douglas - tyson - i won't mention it. douglas won but it was pretty competitive. at no point was douglas having an "easy" time - he was always working, always keeping a distance and maintaining his guard (and in one of the few moments he almost paid dearly). just my opinion i can certainly see if someone wants to mention tyson - douglas even if i don't agree. i'd also give balboa vs clubber lang I (first fight) a mention.
If we talk BIG FIGHT and look at things realistically Holmes - Cooney, tho miles from the top is certainly worth a little mention in the run downs.
I think RJJ-Toney comes close to Calzghe-Lacy. Like some already mentioned, in some people's eyes this represented a battle between two best fighters pound-for-pound. (Though I think Pernell Whitaker may have had something to say about that.) Toney was the more established fighter, and there's no way anyone could imagine him getting beat like RJJ beat him. Roy Jones Jr. was an incredible fighter. At his peak he was one of the best ever.