Madrid, April 11: American tennis star Sere Williams kept her lead in the women's rankings with 8.625 points, while Polish Agnieszka Radwanska returned to the second place, according to the list released on Monday. The Polish player is ahead of German Angelique Kerber, who dropped to the third place with 5.740 points. In the women's doubles, India's Sania Mirza and her Swiss partner Marti Hingis retained their top status in the rankings with 11,825 points. IANS