I'll be No 1 again, says Serena Williams

World No 3 Serena Willams on Saturday vowed to top the WTA rankings again, after finishing a year that saw her make a remarkable comeback from a potentially life-threatening condition.

"I've been No 1 and believe me, I'll be No 1 again," Williams said in Johannesburg during an Africa tour with her sister Venus to promote the sport among young girls.

American Serena Williams with a wheelchair-bound player during a tennis clinic at the Arthur Ashe Academy in Soweto on Saturday. Pics/AFP

Serena finished 1195 points behind top-ranked Victoria Azarenka on the WTA chart, and 645 adrift of No 2 Maria Sharapova. The rankings drew some criticism as Williams beat Sharapova in the WTA Championship in Istanbul last Sunday, and won two Grand Slams this year as well as Olympic gold in the singles and doubles in London.

But Serena wasn't too. "I'm not thinking of it. I'm focusing on the Slams. I had a slow start and that affected my ranking."