Auds were clearly clamoring for HBO’s “Game of Thrones,” whose second season opened Sunday to a series-best 3.86 million viewers, according to Nielsen estimates. The previous best for a single telecast of the show was for its finale last June, which drew 3.04 million.

Additional airings on Sunday drew 1.48 million at 10 p.m. and 943,000 at 11 p.m. for a total of 6.28 million. Last year’s series premiere cumed to 4.22 million for its three airings.

“Game of Thrones” also did a series-best national adults 18-49 rating of 2.0 for its return, well above the 0.9 for its series premiere and the 1.4 for its finale late last spring.

The premiere-telecast audience for “Thrones” on Sunday was considerably larger than that of other high-profile scripted cable shows on the night, including AMC’s “Mad Men” (2.94 million) and “The Killing” (1.80 million for its second-season premiere) as well as Showtime’s “Shameless” (1.45 million for its second-season finale).

“Thrones,” a medieval fantasy series based on George R.R. Martin’s “A Song of Ice and Fire,” is shaping up to be HBO’s second most popular current series, behind only “True Blood,” which regularly topped 5 million regular-timeslot viewers in each of its last two seasons. Another current HBO drama, “Boardwalk Empire,” wrapped its second season by drawing 3 million viewers in its initial telecast last December.

HBO moved quickly to renew “Game of Thrones” for a second season a year ago, pulling the trigger just two days after the show’s premiere. Its debut early last April averaged 2.22 million viewers in its regular 9 p.m. timeslot and its two same-night repeats averaged a combined 2 million more.

The ascendance of “Game of Thrones” has to be comforting for HBO, whose horse racing drama “Luck” ended up wrapping after one season. For its nine-episode run, “Luck” averaged just 575,000 for its initial Sunday telecasts.

Next up for the pay cabler are the premieres of comedies “Girls” on April 15 and “Veep” one week later. They will air in the 10 o’clock hour, following “Thrones.”