HBO’s “House of the Dragon” had some pretty big shoes to fill, following in the footsteps of the mega hit “Game of Thrones.” It seems, fans of the high fantasy series were at least intrigued enough to settle in to watch the first episode of the series, leading to HBO’s biggest series premiere in its history.

On Monday,

revealed that 9.986 million viewers across linear and HBO Max platforms tuned in to watch the first episode of the prequel series Sunday night. This is the largest audience of any new original series in the history of HBO, the company said.

The company said that Sunday night viewership for a HBO series typically represents around 20% to 40% of the show’s total audience.

“It was wonderful to see millions of ‘Game of Thrones’ fans return with us to Westeros last night,” said Casey Bloys, chief content officer for HBO and HBO Max.

“House of the Dragon” tells the story of the Targaryen civil war that took place about 200 years before the events portrayed in “Game of Thrones.” It is based on George R.R. Martin’s novel “Fire and Blood.” Unlike Martin’s other books in the “Song of Ice and Fire” series, this one features an omniscient narrator who documents the histories based on collected accounts of events. In some cases, these stories contradict each other and there are multiple versions of events.

The stakes are high for “House of the Dragon,” which arrived on HBO and HBO Max as newly minted CEO David Zaslav is looking for fat to trim. Cost-cutting measures have become status quo at the recently merged company including layoffs and content eliminations from HBO Max.

As Warner Bros. Discovery seeks to save money, it’s also looking to consolidate its streaming services, something that will be expensive and time-consuming.

“House of the Dragon,” only the second entrant in its Game of Thrones franchise, has a lot to prove, and to live up to. The final season of “Game of Thrones” left a sour taste in many fans’ mouths, as showrunners wrote beyond the events in the material created by author Martin, who has yet to finish the story in his books.

“House of the Dragon” holds an 83% “Fresh” rating on Rotten Tomatoes from 413 reviews, as of Monday afternoon. For comparison, the first season of “Game of Thrones” released in 2011 had a 90% “Fresh” rating. In fact, every season except the final season had a score above 90%. Season eight generated a 55% rating.

Analysts, investors and, most importantly, Warner Bros. Discovery executives will be keenly watching “House of the Dragon’s” viewership metrics going forward to see if it can sustain momentum over the course of the 10-episode series.