I believe the most buys for a heavyweight fight came in the Tyson vs Holyfield 2 fight 10 or so years ago.

Not only was it one of the most popular fights ever, it was also the one where he bit Holyfields ear off. Watched by about 2m people!

I think Lewis Tyson is next, then Tyson vs Holyfield 1.

Oddly, Tyson vs Mcneeley comes in next. Yeah, Tyson vs ? He knocked him out in about 2 minutes, I even remember watching it. It was so big because it was tysons return to the ring after going in jail.