He was a marvel to witness: 'Aladdin' directors on Robin Williams

Robin Williams as gold-hearted Genie in Disney's 1992 "Aladdin" was "jaw-droppingly awesome", say directing duo Ron Clements and John Musker.

The veteran actor-comedian brought to life one of the most loved animated characters and for the directors, watching him create magic with his "mercurial" improvisations, was a treat.

"One of the great joys in all my years at Disney was getting to watch Robin Williams at work on 'Aladdin'... He recorded in four-hour sessions and hardly ever stopped... He was like a tremendous athlete at the top of his game.

"Almost everything he did was great, but there were times when he was especially 'in the zone' on another level and the stuff he was coming up with was jaw-droppingly awesome. He was a marvel to witness," Clements told The Hollywood Reporter.

The actor, aged 67, passed away in August 2014, and Musker said he finds "our world a little dimmer without Robin".

"We wrote 'Aladdin' with Robin Williams in mind... We felt that we could do things with Robin's brilliant mercurial improvs that live action couldn't match. Animated and shaped by Eric Goldberg, I think we did just that. Robin was an absolute joy to work with, indefatigable and generous with his time and unique talents," he added.

Williams had a fallout with Disney after the 1992 film and Dan Castellaneta voiced the Genie throughout the direct-to-video feature "The Return of Jafar", as well as the television series.

Williams again came on board to voice the character for the final time in last installment "Aladdin and the King of Thieves".