'ER' REVERSES FORM IN UNIQUE CHRISTMAS EPISODE AS EVENTS UNFOLD FROM END-TO-BEGINNING

In a form-breaking episode, events just before Christmas are traced in reverse chronological order as a hungover Dr. Kovac's (Goran Visnjic) troubled life lurches closer to tragedy when his car accidentally hits another auto on icy roads -- endangering his passenger, young resident Harkins (guest star Leslie Bibb, "Popular"). While on duty, Kovac struggles to help a sickly young man (guest star Michael Ealy, "Barbershop") fight for his life. In addition, Abby (Maura Tierney) and the emergency room staff attend to a pair of belligerent elves and a young female hockey player (guest star Brittney Lee Harvey) with a head wound. Noah Wyle, Laura Innes, Ming-Na, Sherry Stringfield, Sharif Atkins and Mekhi Phifer also star