When Marshall (Jason Segel) and the gang finds out that Barney (Neil Patrick Harris, front) and Robin (Cobie Smulders, right) are hesitant to define their relationship, Lily (Alyson Hannigan, left) forces them to confront their biggest fear. Meanwhile, Ted (Josh Radnor, center) is anxious about teaching his first lecture at Columbia, on the fifth season premiere of HOW I MET YOUR MOTHER, Monday, Sept. 21 (8:00-8:30 PM, ET/PT) on the CBS Television Network.
