I started this thread almost three years ago due to a heated discussion on a Swedish Star Trek forum regarding whether the joke referred to Bjorn Borg or not. I always thought it did, and was very surprised that a few Swedish trekkers didnīt believe that.
So I bought the First Contact DVD and listened to what Braga and Moore had to say. And of course, the joke refers to Bjorn Borg.
I am not the least surprised since Borg was the best tennis player during the childhood of the script writers.