As expected, Jimmy Kimmel drew big ratings in his debut in the 11:35 p.m. time period Tuesday night, beating both Jay Leno and David Letterman, but it remains to be seen whether he'll be able to hold on to the lead. Preliminary ratings indicated that Kimmel scored a .99 rating among the key 18-49 age group versus a .78 for Leno and a .63 for Letterman. Household ratings had Kimmel ahead with a 2.85 rating and an 8 share, Letterman in second place with a 2.68/7 and Leno third with a 2.41/6. More complete ratings including the number of actual viewers are expected to be released later today (Wednesday). Kimmel's strength was attributed partly to curiosity about what he would say on his opening night in the new time slot, and several writers pointed out that Conan O'Brien also debuted strongly when he replaced Jay Leno on the Tonight Show in 2009, only to see his ratings erode in short order.