TOKYO, Japan - Twelve of the Top 13 ranked players in the world are in action this week at the Toray Pan Pacific Open, led by World No.1 Victoria Azarenka, No.2 Maria Sharapova and No.3 Agnieszka Radwanska.

Though Azarenka hasn't won a title since Indian Wells in March, she is in fine form of late, with her recent results including a bronze medal at the Olympics and a run to the final at the US Open in which she pushed champion Serena Williams to the brink of defeat.

Sharapova will be playing for the first time since her thrilling US Open semifinal loss to Azarenka. She should have plenty of confidence due to her Tokyo résumé, which includes titles in 2005 and 2009 and two semifinal showings. On top of that, only once in her last five events has she failed to reach at least the semifinals - her fourth round appearance at Wimbledon.

Also usually in top form here is Radwanska, as she has never fallen short of the quarterfinals with a 14-3 record. Last year, Radwanska not only took the Tokyo title but went on to win Beijing the very next week. However, she will be seeking to emerge from a bit of a rough patch, having not gone beyond a quarterfinal in the five events since her runner-up showing at Wimbledon.

A couple of others in the draw to watch out for are Angelique Kerber and Sara Errani. Kerber leads the WTA with 56 wins on the season. Errani has just three fewer than that and is coming off a semifinal showing at the US Open.

Coming off deep runs at last week's events are 2010 Tokyo champion Caroline Wozniacki, Kaia Kanepi and Hsieh Su-Wei. Wozniacki will be looking for her first title in over a year in Sunday's Seoul final when she takes on Kanepi, who is in pursuit of her third title of the season. Hsieh was victorious in Guangzhou - her second title of the season.

Two-time Grand Slam champions Vania King and Yaroslava Shvedova are the top seeds in doubles. Seeded second are Nuria Llagostera Vives and Sania Mirza, who are paired up for the first time.