Cardi B Plays Spectator as Middle-Aged Women Battle Over Autograph

Cardi B is worth fighting for ... just ask 2 middle-aged women who were vying for a prized autograph.

We got the rapper leaving 'The Tonight Show' Thursday and the scene cements her position as the hottest female rapper around ... and that's why a John Hancock is so precious.

Cardi only signed for a lucky few, and the 2 women wanted desperately to be in that exclusive club. They go at it fiercely as Cardi hops in an SUV and speeds away.

BTW ... check out her interview with Jimmy Fallon ... it's great.