The singer spilled the beans to Chris Wallace on his weekly show, 'Who's Talking,' opening up about some apparent tension she says manifested on set when they were filming the music video way back in 2001. According to Pink, Xtina confronted her aggressively.

Watch how she describes it ... Pink says it all started because she was sitting in Christina's chair -- unclear if that means on set or off -- which she claims set Christina off. Supposedly, CA was so angry about this ... she was going to "shut down the entire production."

Pink says it didn't actually get physical right then and there, but did make clear ... she relayed to Christina at the time that she couldn't talk to her like that, period. Funny enough, Chris tells Pink he believes she could've kicked Christina's ass ... and Pink agrees.

As for the perceived shade everyone seems to think Pink is throwing Xtina's way ... Pink addressed that too, saying all she's doing is telling a story back as it happened and as she remembers it. If that truth happens to make someone look bad, so be it ... that's her view.

We should note ... Pink has claimed in the recent past that, in another old incident, Christina allegedly tried swinging on her at a club -- although Christina denied that at the time. As for this latest rehashing, we've already heard Christina also considers it old news/MAAN.