IT'S DAY ONE OF THE MERGER, AND THE COMPETITION BEGINS BETWEEN THE RESIDENTS OF MERCY WEST AND SEATTLE GRACE, ON ABC'S "GREY'S ANATOMY"

Guest Starring Hector Elizondo as Callie's Father, Mr. Torres

"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," THURSDAY, OCTOBER 15 (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.

"Grey's Anatomy" is broadcast in 720 Progressive (720P), ABC's selected HDTV format, with 5.1-channel surround sound and Spanish subtitles via secondary closed captioning. A TV parental guideline will be posted closer to airdate.

For more information on "Grey's Anatomy," visit ABC.com.