Lisa Marie Presley's Ex-Manager Sues Her for $800k

Lisa Marie Presley has only herself to blame for her millions of dollars in debt ... so says her ex-manager who is now suing her for $800k he claims she owes him.

Lisa's ex-manager, Barry Siegel, filed new legal docs claiming Lisa twice squandered her father's fortune since she inherited it in 1993. In docs, obtained by TMZ, Barry claims Lisa's excessive spending is what got her into a financial mess and NOT his management of her trust.

What's more ... Barry is suing her to get the $800k he claims she owes him for unpaid work he did before she fired him in March 2016.

As we reported ... Lisa sued Barry back in February claiming she lost $24.5 million after her stock plummeted following an investment into the parent company of "American Idol" ... which went belly-up in 2016.