PREVIEW: GREY'S ANATOMY & PRIVATE PRACTICE

"Invasion" - The residents of Seattle Grace and Mercy West vie for surgeries and their careers as day one of the hospital merger begins. Meanwhile, Arizona stands by an enraged Callie when her father, Mr. Torres, employs a priest to help convince her to date men, and Izzie experiences the brunt of her new surgical competition, on GREY'S ANATOMY, tonight (9:00-10:01 p.m., ET) on the ABC Television Network

GREY'S ANATOMY stars Ellen Pompeo as Meredith Grey, Patrick Dempsey as Derek Shepherd, Sandra Oh as Cristina Yang, Katherine Heigl as Isobel "Izzie" Stevens, Justin Chambers as Alex Karev, Chandra Wilson as Miranda Bailey, James Pickens, Jr. as Richard Webber, Sara Ramirez as Callie Torres, Eric Dane as Mark Sloan, Chyler Leigh as Lexie Grey, Kevin McKidd as Owen Hunt and Jessica Capshaw as Arizona Robbins.

Guest starring Robert Baker as Charles Denman, David Bowe as Don, Sarah Drew as April, Alexie Gilmore as Sarah, Jack Gwaltney as Frank, J.P. Pitoc as Billy, Brandon Scott as Intern Ryan, Kathleen Wilhoite as Leslie, Jesse Williams as Jackson, Nora Zehetner as Reed Adamson, Bruce French as Father Kevin, Freda Foh Shen as Missy Grant, with Hector Elizondo as Mr. Torres.

"Invasion" was written by Mark Wilding and directed by Tony Phelan.

"Right Here, Right Now" - Miranda Bailey brings a kidney transplant patient to Los Angeles, and Addison isn't the only Oceanside Wellness doctor pleased to see her. Meanwhile the consequences of Addison's emotional affair with Noah catch up with her, and Sheldon and Pete finally discover who the father of Violet's baby is, on PRIVATE PRACTICE, tonight (10:01-11:00 p.m., ET) on the ABC Television Network.

PRIVATE PRACTICE stars Kate Walsh as Dr. Addison Forbes Montgomery, Tim Daly as Dr. Pete Wilder, Audra McDonald as Dr. Naomi Bennett, Paul Adelstein as Dr. Cooper Freedman, KaDee Strickland as Dr. Charlotte King, Chris Lowell as William Dell Parker, with Taye Diggs as Dr. Sam Bennett and Amy Brenneman as Dr. Violet Turner.

Guest starring Chandra Wilson as Dr. Miranda Bailey, Brian Benben as Sheldon; other guest cast TBA.

"Right Here, Right Now" was written by Dana Baratta and directed by Rob Corn.