While I usually have a quiet chuckle when I overhear (in person or on the nets) someone stating that they could take a game/set off "x" professional player ... I found the following article an interesting discussion on the whole pro vs pro question (male vs female). Seems that back in 1998 Karsten Braasch, a German journeyman player out of the top 100 played both sisters one set a piece ... and prevailed, despite the pre-match "shandys" and cigarettes.
Read more at: http://observer.guardian.co.uk/osm/story/0,,543962,00.html. This was a friendly match, but the results and Braasch's commentary were interesting.