Blac Chyna Rages When Celeb Boxing Opponent Drops Kim Kardashian Diss

Blac Chyna's already heated before she even steps into a boxing ring tonight ... thanks to the well-timed Kardashian-related jab fired off by her opponent, Alysia Magen.

The Celebrity Boxing combatants, who are fighting in a Saturday night PPV event, came face-to-face for the traditional weigh-in and trash talk moment. They didn't disappoint.

Chyna flexed for cameras as she stepped on the scale, and definitely looks like she's been training hard.

First, Chyna grabbed the mic and told Alysia, "I seen your little rap. It was trash" ... referring to an IG post Alysia made to hype the fight.

Chyna's right. It was trash. However, props to social media influencer Alysia for hitting BC with the best comeback possible.

She said, "Hey, I'm not Kim Kardashian. I'm going to knock you both out!" Chyna lunged at her, but a bunch of people stepped in to break it up.

For the record: Chyna weighed in at 140 lbs. ... one more than Alysia.

Alysia was taking a shot at Chyna and her trainer, Tamara Frapasella-Fortune ... who beat Kim in a 2010 charity boxing match.

Anyway, after Chyna lost the $100 million defamation trial against the whole Kardashian family ... Alysia knows how to hit her where it hurts. At least outside the ring.