Sunday night's primetime coverage of the NFC Championship game between the New York Giants and the San Francisco 49ers on Fox averaged an extraordinary 52.73 million viewers, peaking in the first hour of primetime (7 00 p.m.) with 55.92 million, according to overnight figures released by Nielsen Research. Surprisingly, shows airing opposite The Game were virtually unaffected, drawing ratings that were down a statistically insignificant amount from a week earlier. Perhaps the biggest surprise, however, came after 11 00 p.m. (on the East Coast), when a special edition of Fox's American Idol drew 19.2 million viewers. That resuly may have sent ratings mavens to their record books to determine when, if ever, another entertainment program airing after 11 00 p.m. garnered a similar number of viewers. Ratings for Sunday's AFC championship day game between the Baltimore Ravens and the New England Patriots are due to be released late today (Monday) or early Tuesday.