Though, Serena Williams has claimed four titles this season, she will still end the 2012 season as World No. 3 behind Maria Sharapova and Victoria Azarenka.

Serena claimed Wimbledon title and then went on to earn Olympics gold medal. After taking a short break from tennis, Serena returned to action and won the US Open title and finished the 2012 WTA season on Sunday with the WTA Championships title.

"I think it's a true statement, without trying to sound full of myself or anything," Williams told reporters after beating Russian Sharapova 6-4 6-3 in the final of the season-ending WTA tournament.

"I always said that if I'm playing well and I'm doing everything right it's really difficult to beat me. I still believe that."

Serena Williams finished the year with a stellar 58-4 record and won seven titles. The American missed out WTA mandatory events and Indian Wells and Beijing, the result reflected in Serena’s rankings.

"It's surprising to win two grand slams, the Olympics, Madrid and the Championships and to be number three," said Williams' coach Patrick Mouratoglou.  "If there is a bug somewhere, someone has to find it."