I was currious about the head-to-head records of ten of the last number one ranked players of the WTA (all against one another). While finding the numbers I found some interesting facts. For example the only number one player to have a winning record over Serena is Aranxta, Aranxta has the most lopsided win-lost ratio against the group, and Steffi is the only one in the group that has played everyone on the list and and at the same time no one on the list has a winning record over her.
(First set of numbers is the win lost ratio against the entire group) (The second set of numbers is the over all head-to-head against the group, win-lost-tie):
Steffi- 77 wins 34 loses (she's beaten 7 players- lost to zero- and tied with 2)
Steffi- (77-34) 7-0-2
Hingis- (70-49) 5-3
Lindsay- (62-61) 3-6
Monica- (55-63) 4-5
Venus- (52-36) 5-3
Serena- (43-23) 6-1-1
Araxta- (36-101) 3-6
Martina N-(30-23) 2-1-2
Jennifer- (25-55) 1-8-1
Kim- (19-27) 2-6-1
Martina N has only played 5 of the last 9 number ones Seles is the only player listed here to have a winning record over her, she's tied with Graf in their head to heads.
This was done for pure enjoyment, these numbers don't really mean all that much, but it's very interesting- I thought so anyway.