AMC’s “The Walking Dead,” basic cable’s biggest series of all time, opened its fourth season Sunday with more record numbers.

Despite facing higher-rated sports competition this year from both football and postseason baseball, “Walking Dead” returned Sunday with a monster average audience of 16.1 million viewers — more than 5 million viewers better than last year’s 10.87 million and more than double where it kicked off its second season in October 2011 (7.26 million).

It also did a huge 8.2 rating in adults 18-49, making it easily the top-rated entertainment series telecast of the season, ahead of CBS’ “The Big Bang Theory” (5.5 for its season premiere and a 6.1 for a special second episode right after it).

In adults 25-54, its 7.3 rating ties with the regular-timeslot episode of “NCIS” as the season’s best for an entertainment series. (The second “Big Bang” did an 8.0).

The previous series high for “Dead” — and the all-time best for a cable series — was its third-season finale last spring, which drew 12.42 million and a 6.4 rating in adults 18-49.

By comparison, AMC’s “Breaking Bad” wrapped its run last month with an average audience of 10.28 million and a 5.3 rating in adults 18-49 — easily the best scores for this series.

AMC also scored with post-show “The Talking Dead,” which drew a series-record 5.1 million viewers and a 2.6 rating in adults 18-49.