Stacy Keibler has her husband's back in his war with Cam Newton -- saying the Carolina Panthers QB needs to "do the right thing" and PAY UP for the Bev Hills mansion he allegedly trashed.
TMZ Sports broke the story ... Keibler's hubby Jared Pobre -- who manages a luxury home rental company -- claims Newton wrecked the $11 MILLION mansion where he stayed after the Super Bowl.
Pobre is demanding nearly $300,000 in damages, lost rental income and more.
So, when we saw Stacy and Jared leaving Catch in West Hollywood last night -- we had to ask about the lawsuit .