According to BoxRec the first four nights of fighting at Madison Square Garden were all one fight cards, all featuring Herbert Maori Slade
The Garden’s first four nights:
02/02/1883 Herbert Maori Slade (0-1) – Jim Mace (1-0) NC 3/3
03/06/1883 Herbert Maori Slade (0-1) – Jim Mace (1-0) NC 3/3
04/27/1883 Herbert Maori Slade (0-1) – Joe Coburn (debut) NC 3/3
08/06/1883 John L. Sullivan (17-0) – Herbert Maori Slade (0-1) TKO 3/4
From BoxRec: The exotic Maori was basically a large punching bag. Sullivan put Slade down several times without much resistance.
Gosh! - If Slade could just have won that last fight, we today might be calling the Garden ‘the house that Slade built.’
If you look at Slade’s record (http://boxrec.com/boxer/32606) the Slade-Mace encounters look to be more a carnival act than prize fights; fourteen fights, all for three rounds, all NCs. They came out of New Zealand together, fought a few times at the Garden and then put their show on tour in The United Kingdom.
One might argue that the first ‘real fight’ at MSG featured the Great John L against some guy named Maori-Slade.