If, as it is said, it's not easy being green, the producers of the third animated movie about a green ogre suspect that it's especially not easy being greener than the third movie about a superhero that opened two weeks ago. Dreamworks Animation chief Jeffrey Katzenberg told reporters at the Cannes Film Festival Thursday that he doubts that Shrek the Third will exceed the record ticket sales of Spider-Man 3, which opened with $151 million at the domestic box office. "I hope we have a very, very good weekend, but I don't expect us to set any records," Katzenberg said. Most box-office analysts are predicting that the latest installment will earn about the same as the last one did in its debut -- that is, in the neighborhood of $100-110 million. Online ticket sellers Movietickets.com told Reuters that presales have been about the same as those for Shrek 2, while rival Fandango.com claims that the latest movie is outselling its predecessor by more than 2-1. Although the film is regarded as critic-proof -- the initial reviews were mostly atrocious -- it has other factors working against it, not the least of which is the fact that it is likely to attract a greater number of families buying discounted children's tickets than Spider-Man 3. Moreover it is opening on 4,122 theaters -- a huge number, except when one considers that Spider-Man 3, which had already set a record for the widest North American release, will be expanding to 4,324 theaters this weekend. Spidey is expected to continue to perform strongly and draw moviegoers away from Shrek. Finally, there is the worrisome issue of Shrek 2's DVD sales, which failed to fulfill expectations, resulted in a huge fall in the company's stock, and raised questions about the continued appeal of the Shrek franchise.