The war between Claressa Shields and Laila Ali is even nastier BEHIND THE SCENES ... with Claressa revealing all the trash-talking messages they've been sending each other -- and it's WILD!!
Shields -- BY FAR the best active female boxer on the planet -- says she offered up an olive branch to Ali back in January, after Laila trashed her on 'Sway in the Morning.'
If you recall, 42-year-old Ali (24-0) said she would destroy Shields if they ever fought because Claressa isn't talented enough to hang with her.