According to BOXOFFICE.com’s Early Weekend Estimates, Michael Jackson’s This Is It will win the weekend box office with an estimated $21.5 million. Sony’s concert documentary centered on the last rehearsals of the late pop icon experienced a solid Friday jump, but Friday’s spike in attendance wasn’t nearly strong enough to make up for the film’s modest start on Wednesday and Thursday. This Is It is on course for a five-day start in the area of $33 million. Under normal circumstances that would be a great start for either a concert film or a documentary, but the figure is somewhat underwhelming in this case given the reported $60 million Sony spent to acquire the film’s rights and the fact that This Is It is currently scheduled for a limited engagement window of only two weeks.

Paramount’s Paranormal Activity continues to impress, as it is on pace for a very nice second place performance over Halloween weekend. The ultra low-budget horror film should scare up roughly $18 million for the weekend. That places it within shouting distance of This Is It for the weekend, which is something that simply wasn’t expected this time a week ago. The cume for Paranormal Activity will stand at just over $86 million at the end of the weekend, though the film could fall off much faster going forward once the build up to Halloween is behind it.

It should be a close race for third place between Overture’s Law Abiding Citizen and Universal’s Couples Retreat. With Law Abiding Citizen likely to be the more popular Halloween choice of the two, look for it to edge out Couples Retreat just slightly for the three-day frame.

Despite having Halloween appeal, both Warner’s Where the Wild Things Are and Lionsgate’s Saw VI are on course to experience large weekend declines. The films will occupy fifth and sixth places this weekend and both should continue to fade away very quickly in the days and weeks after Halloween.