(Cover) - EN Showbiz - Scarlett Johansson reportedly thinks Mark Ruffalo is the secret to success of Avengers Assemble.

The stars appear in the superhero movie, playing Black Widow and The Hulk respectively. The film has topped charts the world over, grossing over $1 billion so far.

Scarlett was overheard telling a friend why she thinks it has done so well while at the exclusive Chateau Marmont in Los Angeles recently.

"I can't take the credit. It's not about me. It's not even about the special effects. Mark's unbelievable, fantastic, amazing and he makes the movie what it is," she said, according to National Enquirer.

Robert Downey Jr., Chris Evans, Chris Hemsworth, Samuel L. Jackson, Tom Hiddleston and Jeremy Renner also appear in the movie. The whole cast were supportive of each other and director Joss Whedon was amazed by how well they got on.

"These guys really like each other," he laughed. "My biggest problem is to get them to shut up so I can shoot." (C) Cover Media