Just two days after the Season 4 premiere delivered a series-high 6.6 million viewers, HBO announced it has renewed Game of Thrones for two more seasons.

"Game of Thrones is a phenomenon like no other," HBO programming president Michael Lombardo said in a statement. "David Benioff and D.B. Weiss, along with their talented collaborators, continue to surpass themselves, and we look forward to more of their dazzling storytelling."

The audience for Sunday's premiere is the cable channel's largest since the 2007 finale of The Sopranos, which drew 11.9 million viewers (two replays brought the Game of Thrones total to 8.2 million). It represents a 52 percent increase from the Season 3 opener.

Game of Thrones airs Sundays at 9 p.m. ET/PT on HBO.