Wilder died on Sunday (28Aug16), aged 83, due to complications from Alzheimer's disease.

The screen legend had kept his illness a secret from fans until his passing, but Brooks admits he had been told of his condition, and while he knew the end was near for Gene, he still can't quite believe his old pal is dead.

"He was sick and I knew it, he was such a dear friend... I expected he would go," Mel revealed during an appearance on America's The Tonight Show Starring Jimmy Fallon. "But, when it happens, it's still tremendous, it's still a big shock.

"I'm still reeling from no more Gene, I can't call him (anymore)... He was such a wonderful part of my life."

Brooks went on to recall his first film collaboration with Wilder, 1967 The Producers, a project Gene was convinced would never get funded.

After telling Gene he would star as Leo Bloom, the frizzy-haired actor sarcastically responded, "You're doing a play about two Jews who are producing a flop instead of a hit, knowing they can make more money. And the big number in it is Springtime for Hitler. Yeah, you're going to get the money!"

Brooks did secure financing for the comedy musical, and after learning he would be heading to the big screen for the first time, Wilder became emotional.

"He burst into tears and held his face and cried," Brooks remarked. "I hugged him. It was a wonderful moment."