Credit: FX; CW

Siobhan better watch her back!

The CW has snagged Rescue Me vet Andrea Roth for a recurring role on Tuesday night's freshman breakout Ringer, reports.

Roth, 44, who appeared as Denis Leary's wife for all 93 episodes of the FX firefighter drama's run, will be introduced to Ringer fans as the estranged ex-wife of Andrew (Ioan Gruffudd) and mom of bratty Juliet (Zoey Deutsch).

Her character, Catherine, will instantly show off a mean streak as soon as she hits New York City and is introduced to Siobhan (Sarah Michelle Gellar), the woman who stole her husband.

Ringer airs Tuesdays at 9 p.m. (EST) on The CW.