"I Can Whip Any Mechanical Robot" by Jack Dempsey (1930s)
The 1979 book Wasn't the Future Wonderful? features the above two-page spread of Jack Dempsey challenging a robot. Unfortunately, the book doesn't specify the publication or date except that it's from the 1930s and probably from Modern Mechanix. Below is an excerpt from the piece.
I can whip any mechanical robot that ever has or ever will be made.
Maybe that sounds a bit egotistical, maybe you will say it's just the voice of a "has-been," but I assure you that neither is true.
Engineers can build a robot that will possess everything except brains. And without brains no man can ever attain championship class in the boxing game.