Simona Halep has secured the year-end number one ranking for the second straight year.

The 27-year-old Romanian will have amassed a total of 53 weeks as the world No.1 when the 2018 season ends, the WTA said on Monday.

Halep, who won her first major title at this year's French Open, may have to pull out of the season-ending WTA Finals because of a back problem.

"Finishing the season as the WTA world No.1 last year was a huge honour for me,” said Halep, quoted by the WTA website.

"To do it for a second time in 2018 feels like a special achievement, especially having also won my first Grand Slam this year.

"To be able to see my name again alongside the other legends who have achieved the year-end No.1 ranking makes me very proud."

Halep became the 25th player to reach the WTA world No.1 ranking on October 9, 2017 and spent 40 weeks in the top spot this year.

WTA top 10 as of October 15 (previous ranking in parenthesis):

1. (1) Simona Halep, Romania, 7,421 points
2. (2) Caroline Wozniacki, Denmark, 6,461
3. (3) Angelique Kerber, Germany, 5,400
4. (4) Naomi Osaka, Japan, 4,740
5. (6) Karolina Pliskova, Czech Republic, 4,465
6 (5) Elina Svitolina, Ukraine, 4,350
7. (7) Petra Kvitova, Czech Republic, 4,255 
8. (8) Sloane Stephens, United States, 4,022
9. (9) Julia Goerges, Germany, 3,785
10.(10) Kiki Bertens, Netherlands, 3,740