Henin vs. Serena
When will, or will, Justine pass Serena in terms of 'greatness'. Serena currently has 8 majors; Justine 6. The way it has been going lately, Justine will pass Serena. (Since Justine won her first Slam; Serena has won 3, Justine 6 ... ). Justine has been able to stay healthy easier than Serena, which means she's able to play more, which means she will win more titles. Justine's also been year end #1 more times than Serena, and has an Olympic singles medal, which Serena does not have.
So what will it take? 2 more Slams? Just a Wimbledon title? 3 more Slams?