Victoria Azarenka has admitted that it is an "incredible achievement" for her to end the year as the world number one.
The Belarusian made sure of the feat with victory over Li Na at the WTA Championships in Istanbul on Friday night.
The 23-year-old is only the 11th player to finish the season at the top of the rankings since they were established in 1975.
"It's kind of difficult to believe that a little girl from Belarus is on that list, but it's really an incredible achievement," she said.
"When I started to play tennis I had this big picture in my head that I want to be there. Back then it was so far away. It was like pretty much touching the sky."
Azarenka will meet world number two Maria Sharapova on Saturday for a place in Sunday's WTA Championships final.
