On Sunday, 1.3 million viewers tuned in to watch "Leaving Neverland," HBO's explosive Michael Jackson documentary, during its two-hour premiere, according to Nielsen.

Part two of the documentary pulled in 927,000 viewers on Monday, The Hollywood Reporter reported.

Sunday's premiere was the third-most-watched documentary debut for HBO in the past decade, behind "Going Clear" and "Bright Lights," according to The Wrap.

In Britain, the viewership numbers were significantly higher on Wednesday and Thursday when the documentary aired on Channel 4.

"Leaving Neverland" secured a huge audience for HBO.

Part one of HBO and director Dan Reed's four-hour documentary, which details allegations of child sexual abuse against Michael Jackson, was viewed by 1.3 million people during its premiere on Sunday, according to Nielsen, The Wrap reported.

Part two of "Leaving Neverland" pulled in 927,000 viewers on Monday for a two-night average viewership of 1.1 million, The Hollywood Reporter reported.

The Wrap reported Sunday night's premiere was the third-most-watched documentary debut for HBO in a decade. It follows the premieres of the 2015 Scientology doc "Going Clear," which had 1.7 million viewers, and the 2016 Carrie Fisher and Debbie Reynolds doc "Bright Lights," which had 1.6 million viewers. But including all on-demand and digital platforms, "Leaving Neverland" was viewed by 1.7 million.

In Britain, the numbers were even higher. An average 2.1 million viewers tuned into part one when it aired on the UK's Channel 4 on Wednesday, and 1.9 million people watched part two on Thursday, Variety reported. The numbers are over double the usual audience for Channel 4 at 9 p.m., according to Variety.

In "Leaving Neverland," two men, Wade Robson and James Safechuck, say they were in sexual relationships with the pop singer when he was at the height of his fame in the late 1980s and early '90s and they were young boys.

Both parts of "Leaving Neverland" are available to stream on HBO Go and HBO Now.

Read more of Business Insider's coverage of "Leaving Neverland":