It was all football, all the time in millions of American households Sunday as CBS scored strongly in the afternoon and in early primetime, Fox competed in a handful of markets with local NFL games, and NBC dominated primetime with Sunday Night Football. The overrun on CBS, which finished at 7:37 Eastern Time, drew 18.7 million viewers. During that same period, NBC's Football Night In America was being watched by 9.7 million viewers, while the limited NFL overrun on Fox produced 6.2 million viewers. NBC's Sunday Night Football contest between the Detroit Lions and the San Francisco 49ers averaged 17.7 million viewers, according to the overnight ratings -- down from the season opener a week ago but still good enough to give NBC a win for the night.