Fox had little competition in prime-time Sunday night in the key 18-49 demographic as the Indianapolis Colts beat the New York Giants 20-12. 

According to early numbers from Nielsen, the preseason NFL game drew an average of 5.8 million viewers and a rating of a 1.9 in adults 18-49. Fox easily won the night in the demographic, while CBS came in second with a 1.2.

In metered markets, the NFL telecast scored a 4.9 rating, up 58% from last year’s second Fox preseason NFL game. 

PHOTOS: Cable versus broadcast ratings

However, CBS got the top spot in viewership with the help of "Big Brother," which has been controversial because of the behavior of some of its contestants.

The show brought in 6.52 million viewers, making it the most-watched telecast of the night in prime time, and scored a 2 in 18-49. "Big Brother's" ratings were down from last week. 

The ABC reality series "Secret Millionaire" increased its rating 9% to 1.2 this week, while "Whodunnit" jumped 27% from last week to grab a 1.4 rating in 18-49 and hooked 3.7 million viewers.

NBC's cop show "Crossing Lines" finished out the season with a low 0.4 rating and barely more than 2 million viewers. 

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ryan.faughnder@latimes.com