Amazing stuff from MLDB.   Hingis was also on the WTA tour at 14 (I think), winning Wimbledon at 15 (or was it 16 ?) which is probably the most impressive achievement of them all.  Vaidisova also did big things at 15, she was on the WTA tour then.

The reason why Karantcheva and Vaidisova are exceptions to the norm in doing so well so early must largely related to the fact that their physical development was so fast. They both looked like they were 20 at 15.

Karantcheva was so stupid to take drugs though, if you have that much talent, what's the need !