Simona is a Romanian professional tennis player. The Women's Tennis Association (WTA) ranked her world No. 1 in singles on two separate occasions between 2017 and 2019. She reached the No. 1 ranking for the first time on 9 October 2017. On her second occasion, she held the ranking for 48 consecutive weeks. In total, she has been No. 1 for 64 weeks, which ranks tenth in the history of female tennis. Halep was the year-end No. 1 in 2017 and 2018.