Serena Williams beat her sister, 6-2, 7-6 in the finals of the year ending Sony Ericsson Championships in Doha on Sunday. Serena was undefeated this week and will end the year as the best player in the world – both in ranking points and by popular consensus. Besides the ranking, prestige and the 1.5 million dollar pay day, Serena mentioned that she was thrilled to “finally” win a non-Major tournament, her first since taking the title in Charleston in April of 2008.

Here’s Serena with her No. 1 trophy, her first since 2002:

But Serena wasn’t entirely satisfied, when an interviewer congratulated her on her strong finish to the season, she replied: “I wish we could have won the doubles, but that didn’t work out.” (click here for the interview)

She and Venus paired up this year to win doubles titles at the Australian, Wimbledon and the US Open, admitting this week that is was their “secret goal” to compete in doubles in Doha. It was likely that their other secret goal was to win the tournament, but they were knocked out by Nuria Llagostera Vives and María José Martínez Sánchez in the semis. The Spanish duo proved that their victory was no accident, going on to beat the No. 1 ranked team of Liezel Huber and Cara Black: 7-6 (7-0), 5-7, 10-7 in the final.

By the way, check out the amazing Spanish cheering section that helped cheer the Spaniards to victory this week – eat your hearts out, Samurai!

The WTA action isn’t quite over yet. There’s still this coming week’s Commonwealth Bank Tournament of Champions in Bali, “a season-ending event for the Sony Ericsson WTA Tour’s top International tournament winners.” Marion Bartoli and Sam Stosur are the top seeds. Click here for more.