Re: The Big Four?
Why 4? The days of Henin, Clijsters, Serena and Venus are GONE. We're in a new Era.
Why i think of the big players, i think of players who put fear into their opponents. Justine does that, Serena does that (though she is losing it a bit not playing much / being in shape - but the AO was a good step), Venus lost it (losing to anyone) but she is working on getting it back. Ivanovic is building it fast - she hits the ball harder than anyone. Jankovic is almost there, but she's a mental doubt.
To this list i'd add Kuznetsova. She is one of the most complete players, with a dangerous game. If she can get her head together - watch her to be right up there.