Brandy & Monica Bring Out LL Cool J, Mario, OT Genasis, Blxst in L.A.

Brandy and Monica took full advantage of the Hollywood access lanes during their 2nd L.A. stop for their "Boy Is Mine" tour ... rolling out the red carpet for O.T. Genasis, Mario, Blxst, and the one and only LL Cool J!!!

The festivities went down inside the KIA Forum, and TMZ Hip Hop obtained plenty of video ... O.T. popped out to perform his hit record "Cut It" while LL had the crowd "Doin It" wild.

Mario showed the crowd in real time why he's confident in critiquing his fellow singers with a slam-dunk rendition of his billion-streamer "Let Me Love You" ... and Blxst repped hard his and Brandy's World Series-winning hometown, ripping through his double-platinum classic "Chosen."

Tour opener Kelly Rowland also gave audiences the best of both worlds ... her own solo hits in addition to doses of her Destiny Child's reign when she, Beyoncé, and Michelle ruled the world!!!

Brandy and Monica also poked fun at their music industry beef back when they were teens, with "The Boy Is Mine" becoming the biggest song on the radio before it was certified Diamond.