Rena has about 6/7 years left in her. She isn't going to be winning slams in bunches for more than 3/4 years, however. She starts with 7 slams. I think, realistically, she will finish her career with between 12 and 18 slams. Maria Sharapova has the most potential. She has one, but has 12 years left in her, with 9/10 years of heavy slam winning potential. She could end up with 22 grand slams easily.