WATCH: 'Avengers' cast show off their singing skills

It is widely expected to be a massive success at the box office this weekend and beyond, but who knew how well the cast could SING?

Well, most of them.

Here's a little vid put together by The Tonight Show Starring Jimmy Fallon:

The cast of Avengers: Infinity War sing their own version of "The Brady Bunch" theme song, "The Marvel Bunch."