LOS ANGELES, United States (AFP) — Warner Bros’ Joker: Folie a Deux, a dark new musical Batman spin-off, earned an estimated US$40 million over the weekend to top the North American box office, industry watchers reported Sunday.

But that was far behind the US$96.2 opening of the original Joker in 2019, a movie that earned Joaquin Phoenix a best actor Oscar and grossed more than US$1 billion worldwide.

Industry analyst David A. Gross called it “a weak opening for the follow-up sequel in a superhero series”.

“Folie a Deux”, French for “shared madness”, again stars Phoenix as the unbalanced titular villain, this time joined by Lady Gaga (playing the cheerily deranged Harley Quinn) as the two sing, dance, and plan assorted acts of mayhem.

Todd Phillips directs, and the cast includes Brendan Gleeson and Catherine Keener.

Last week’s box office leader, family-friendly sci-fi tale The Wild Robot from DreamWorks Animation, slipped a spot to second, taking in US$18.7 million for the Friday-through-Sunday period, industry watcher Exhibitor Relations estimated.

Lupita Nyong’o voices Roz, an intelligent robot who is marooned on an uninhabited island, and to survive has to befriend a menagerie of woodland animals, and ends up adopting an adorable gosling.

Warner Bros’ Beetlejuice Beetlejuice also slipped a spot, to third, earning US$10.3 million.

Michael Keaton again plays the creepily hilarious title character with Winona Ryder reprising her role as Lydia Deetz, backed by Beetlejuice newcomers Jenna Ortega, Monica Bellucci and Justin Theroux.

In fourth was Paramount’s animated action film Transformers One, the latest installment in the toy-based franchise, at US$5.4 million.

And in fifth, for the second-straight week, was Speak No Evil, a psychological horror film from Blumhouse and Universal Pictures, at US$2.8 million. James McAvoy and Mackenzie Davis star.