St. Petersburg, FL -- (Sports Network) - Just one week after losing her top ranking to fellow Serb Jelena Jankovic, Ana Ivanovic has returned to No. 1.

Ivanovic is assured of being No. 1 for at least the next two weeks, which would mark her 10th and 11th weeks at the top. The French Open champ was No. 1 for nine weeks before being supplanted by Jankovic last week. Jankovic became the 18th woman to reach No. 1, despite having never even reached a Grand Slam final.

The 20-year-old Ivanovic has performed in three of the last six major finals, going 1-2. She was this year's Australian Open runner-up to former No. 1 Maria Sharapova and gave way to Justine Henin in last year's French Open finale.

Ivanovic, who defeated Russian Dinara Safina in the 2008 Roland Garros finale back in June, will be the top seed at the U.S. Open, which will get underway next week in New York.