The "open era" in tennis refers to the opposite situation: where the grand slam tournaments are open to professionals. Amateurs were always allowed in. https://

The "open era" in tennis refers to the opposite situation: where the grand slam tournaments are open to professionals. Amateurs were always allowed in. https://en.wikipedia.org/wiki/History_of_tennis#Open_Era https://en.wikipedia.org/wiki/History_of_tennis#Open_Era