Can anyone give some perspective on how tough a task Laver's '67 pro slam was vs., say, his '69 open slam? For example, how many players entered the pre-open pro tournaments? I'm guessing it wasn't very many, because from what I know of those days, there simply weren't very many pro players. I saw a post from Carlo Giovanni Colussi of this forum giving his opinion of the best pro + am players in that year. He has Laver-Rosewall-Gimeno, all pros, at 1-2-3, then a group of two pros and two am players (in no order, Stolle, Ralston, Newcombe and Emerson), and then a group of two pros and three am players (in no order, Gonzales, Buchholz, Mulligan, Roche and Santana). So if Carlo is right, only 7 of the top 12 in 1967 were pros, and I bet the further down the rankings one looked, the more amateurs would dominate. That all leads me to wonder how tough of a task winning a pros-only tournament was vs. an open tournament. Obviously, with Rosewall, Gimeno and Pancho around, it couldn't have been easy for Laver. But is it fair to give the '67 pro slam as much weight as an open slam?