Giants vs. Packers normally is a sure-fire ratings winner for NBC’s “Sunday Night Football,” but the game took an expected hit from the second Presidential debate between Hillary Clinton and Donald Trump.

The Packers’ 23-16 victory averaged 16.6 million viewers, down from NBC’s prior Sunday night average of 22 million.

The impact of the debate was evident in the quarter-hour-by-quarter-hour numbers.

The game peaked at 20.5 million viewers from 8:45 to 9 p.m., just before the debate began, and recovered to an average of 17.2 million from 10:45 to 11:30 p.m., after it was over.

Still, it could have been far worse.

Preliminary figures showed the debate viewership down about 25 percent from a record 84 million for the first one on Sept. 26, which clobbered ESPN’s “Monday Night Football.”

The “overnight” rating for Sunday’s game was 10.2 percent of homes in major markets, the lowest for a Sunday night since Packers-Vikings did a 9.9 against Game 4 of the Red Sox-Cardinals World Series in 2013, according to Sports Media Watch.

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“SNF” had a record-low overnight rating of 7.2 for a Seahawks-Buccaneers game that was shown opposite Game 7 of the Red Sox-Rays ALCS in 2008.

Milwaukee ranked first among the 56 markets measured with 43.7 percent of homes watching. New York, which was the highest-rated market for the first Presidential debate last month, ranked 10th at 12.2.