The way the season has gone for Serena Williams, there was only one fitting way for it to end.

Williams capped a career year in style on Sunday, earning her 11th title by coming from behind to beat Li Na 2-6, 6-3, 6-0 for her second straight WTA Championships crown.

Williams became the eighth woman to win 11 or more titles in a year and the first since Martina Hingis had 12 in 1997.

The American also is the first to repeat as champion at the season-ending WTA Championships since Justine Henin in 2007.

"It was an awesome year," said Williams, who sank to her knees after firing a backhand winner on her second match point.

The victory brought Williams' prize money total for the year to $12,385,572. The only player, male or female, to earn more in a year was Novak Djokovic with $12,803,737 in 2012 and $12,619,803 in 2011.

Williams won the event for the fourth time, having also captured the elite tournament for the top eight players in 2001, 2009 and 2012.

Williams has won 78 of 82 matches this year and will finish the year as the top-ranked player for the third time in her career after 2002 and 2009.

Her titles this year included the French and US Opens for a total of 17 Grand Slam crowns. Her winning percentage of .951 is the best on the tour since 1990.

Martina Navratilova had a record of 86-1 and a .989 percentage in 1983.

Still, Williams said she would have preferred to have won at least one more Grand Slam title.

"I live to win slams. I mean, obviously I'm so excited to be the WTA champion," Williams said. "I can't say it's the best (season). I don't know. I really don't know."

Li was in her first WTA Championships final and will finish the year at a career-high No 3.

The final featured two players over the age of 30 for the first time in the championships' 43-year history. Williams is 32 and Li is 31, but both are playing some of their best tennis.

Li got off to a better start over a sluggish-looking Williams, who struggled a day earlier to beat Jelena Jankovic and complained later of being exhausted after a long season.

"I felt good this morning, much better than I did yesterday, but then in practice I was like, 'Oh, no.' I was a little worried, but I just hung in there and just kept going and going," Williams said.

Li also said she was tired.

"After a set and a half, I was feeling no more energy left. It's a tough tournament, because I played five days in a row," said the Chinese star. "Every opponent (is in the) top eight, so you never have an easy match in this tournament."

It was another double-fault by Li that gave Williams a break of serve at the start of the third and the American pulled away.

Williams had to save five break points, the last one with her sixth ace, before wrapping up the title.

Li, the 2011 French Open champion, fell to 1-10 against Williams. She lost a set 6-0 for the second straight time they played. She won only three games in her loss to Williams in the semifinals of the US Open.

"I have a little bit of bad taste, because it was at love, but I still feel positive things," Li said.