O.T. Genasis Punched Guy Who Confronted, Sparked Fight with Nipsey Hussle

O.T. Genasis is technically the reason Nipsey Hussle got roped into a brawl, 'cause the dude who confronted Nip had just gotten socked by O.T. ... and confused the two.

We got footage of O.T. getting into a fight inside of Nightingale in WeHo Sunday night just moments before the rapper ran into Nipsey outside, who was just arriving with his gal. In this clip, obtained by TMZ, you can see that the guy O.T. throws a haymaker at, is the same dude who confronts Nipsey outside as he and O.T. try making their way back in.

As we reported ... it was a classic case of mistaken identity, but now we know it was O.T. that the aggressors were after. Look at their outfits -- Nip and O.T. are both wearing plaid, which is presumably why the gentleman in white thought Nipsey had punched him.

Luckily for everyone, the madness had dispersed by the time cops showed up on the scene. No arrests were made, but a taser was pulled out at one point to de-escalate things.