The 30-year-old Russian had a signature win at Tokyo, defeating three Top 10 players in a row, including No. 3 Agnieszka Radwanska
for the championship, to earn 900 points and a cool $385,000.
Petrova started the year ranked 31st, but a 34-17 record has moved her to her highest mark since the end of the 2010 season.
At the other end of the spectrum this week is former world No. 2 Vera Zvonareva
, the 2011 Tokyo runner-up. Inactive since the Olympics, Zvonareva plunged 29 points to No. 48 this week, and is just 11-9 in 2012. It's a staggering drop for the player who started the year ranked No. 7 in the world and was No. 2 as recently as August of 2011.
Also making a positive move in the Top 50 this week is China's Zheng Jie
, who improved five spots to No. 22. Zheng picked up 70 points with a trip to the second round of Tokyo and improved to 26-20 in 2012.