Update: Here's ABC's take.
“Lost” (9:00-10:00 p.m.)
Opposite the second hour of Fox’s 2-hour “American Idol” (featuring Top 10 female performances) from 9:00-10:00 p.m., ABC’s “Lost” surged over its lead-in by 4.9 million viewers (9.2 vs. 4.3 million) and by 150% in young adults (4.0/10 vs. 1.6/4) and grew its numbers from start to finish (+3% in viewers/+5% in young adults). Despite CBS’ (original “NCIS”) and NBC’s (first hour of “Biggest Loser”) decided lead-in advantages coming into the time period, ABC’s “Lost” defeated its non-“Idol” competition in the 9 o’clock hour by wide margins in Adults 18-49 (4.0/10), outpacing the second hour of NBC’s 2-hour “Biggest Loser” by 25% (3.2/8) and CBS’ original “NCIS: LA” by 29% (3.1/8).
“Lost” finished as Tuesday’s No. 1 scripted TV program for the 5th consecutive week in Adults 18-34 and among key Men (M18-34/M18-49).
Source: ABC
Source: TVByTheNumbers