No matter how hard Shrek tries, Eddie Murphy's smart-ass donkey just won't shut up!

While the directors were laughing at Myers, they also closely listened to what he was saying. Many of Myers' offhanded comments became key to finding Shrek's character. "They certainly helped the character evolve. Because we were constantly working the sequences, some of his earliest ad-libs helped us find a direction for a particular sequence," explains Jenson. "Even after we layered some sequences, he'd say, 'You know what would be a great line right here?' and we'd go back and put it in."

Murphy, on the other hand, took a much more serious approach to his character. As the sassy, self-effacing sidekick, he gets most of the film's funniest punchlines. The comedian therefore focused the lion's share of his energy on his performance. "He almost had blinkers on until he got behind the microphone and then -- boom -- he was the character," says Jenson. "He would grill us on something if he didn't understand it. But once he got the concept, he would completely own it. Sometimes he'd end up with something we didn't expect, but it was always funnier than we'd expected."

Co-directors Andrew Adamson and Vicky Jenson.

On Co-Directing
Jenson describes her partnership with Adamson as being "kind of separate and kind of side-by-side." During the early stages of story development, the duo was virtually inseparable as the action unfolded. As Shrek began to take shape and specific segments were agreed upon, the directors split the film in half -- each working on a specific number of scenes.

"That way we could focus our attentions on all of the tiny details of each sequence; from story to production design through the editorial process where you are constantly with the animators," continues Jenson, who added that each director was also in charge of his or her particular scenes when the actors were in the recording studios.

The partnership also meant a constant dialogue between the two. Neither went very far in the process without input from the other. "I'd work on a sequence with a story artist for a week or so, then after it got to a certain stage we'd present it to Andrew and our producer," says Jenson. This also held true during the animation process where the directors reviewed all of the dailies together. "Even though there'd be a lead director on a particular shot, we would discuss it," she continues. "We would discuss it with the other animators as well -- what was working and what we could make better."

Jenson does admit she had a particular preference to which scenes ended up in her charge. "I tended to gravitate to some of the more goofy sequences," she says. "My background is 3D. I worked with Ralph Bakshi and John Kricfalusi. So I look at comedy just by itself. If it's entertaining -- let's keep it. Let's never lose a laugh."