LOS ANGELES, Oct. 13 -- Tron: Ares,the latest installment in the Disney sci-fi franchise, debuted atop the North American box office, industry estimates showed yesterday, but analysts said its US$33.5 million haul was disappointing given its huge budget.

"The movie was tracking well, but interest stalled during the last 10 days and the opening dropped," said David A. Gross of Franchise Entertainment Research.

"This is a weak opening for the 3rd episode in a science fiction series."

Tron: Ares-which stars Jared Leto, Greta Lee and Evan Peters-tells of mankind's first encounter with artificial intelligence in the real world.

Experts and industry press said it cost US$180 million to make.

In second place at US$8 million was another new ...