Jelena Jankovic was today officially confirmed as the world number one, dislodging Serena Williams from the top of the rankings.
This marks the second stint at the summit for Jankovic, who also held the spot for one week in August.
Williams had held the honour for the last four weeks after defeating Jankovic in the US Open final.
However, Williams' stunning second-round loss to China's Li Na last week in Stuttgart guaranteed the 23-year-old Serb the top spot in today's updated rankings.
Jankovic went on to win in Stuttgart and, with her victory in Beijing a week earlier, won back-to-back titles for the first time in her career.
Her 4,230 ranking points have her 213 points clear of Williams. Third-ranked Dinara Safina is 448 points off the lead.
"I'm happy the hard work I've put in is paying off," said Jankovic, who has won nine of 10 matches since her loss at Flushing Meadows.
"I've been playing very well since the US Open and my confidence is quite high. My main goal is to finish the season at number one."
Jankovic has won more matches than any other play on tour this year, compiling a 59-16 record in 19 tournaments.
She has won three titles this season and eight overall, but remains the only number one in the history of the WTA rankings to have never won a grand slam title.