GREY'S ANATOMY - "Poker Face" - After being blackballed by most of the surgeons, Meredith uses Lexie to spark Derek's interest in her patient's rare brain tumor case and, in secret, gives guidance to April with Bailey's clinical trial; Callie's wish for Arizona and Mark to form a friendship comes to fruition and she realizes it's more irritating than helpful; Alex and Teddy research alternative surgeries for a very superficial patient; and Callie and Cristina struggle with a very difficult spinal surgery, on Grey's Anatomy," THURSDAY, OCTOBER 20 (9:00-10:02 p.m., ET) on the ABC Television Network. (ABC/RON TOM) ERIC DANE, JESSICA CAPSHAW