The 23-year-old's recent form includes third round defeats at Wimbledon and last week's Rogers Cup, and a first round loss at the French Open in May.

Kontaveit, who ranked 14th in April, is next in action Monday at the Cincinnati tournament, one of several warm-up events to the U.S. Open which starts on Aug. 26. She faces former world number one Angelique Kerber of Germany.

Meanwhile, Estonia's other top two tennis players also slipped down the rankings. Veteran player and former Wimbledon quarter finalist Kaia Kanepi fell five spots to 77th. Recent highlights for the 34-year-old, from Haapsalu, include reaching the last 16 at the French Open.

One player to buck the trend is Elena Malõgina; the 19-year-old rose 30 places and now stands at 715th in the WTA (women's) rankings.

Top men's player Jürgen Zopp, who failed to qualify for Wimbledon this year, fell 23 places to 447th in the current rankings. Vladimir Ivanov and Kristjan Tamm lie in 790th and 868th places respectively.

Naomi Osaka (Japan) is now WTA number one, ahead of Ashleigh Barty of Australia. The pair had earlier shared the number one spot. Karolína Plíšková (Czech Republic), something of a nemesis for Kontaveit having putting her out of the Rogers Cup last week and beaten the Estonian on two earlier occasions, is third, with former world number one Simona Halep (Romania) fourth and another Czech player to have rained on Kontaveit's parade in recent months, Petra Kvitova, in fifth place. Kvitova defeated the Estonian player in the Stuttgart final in April.

The big three mens' players, Novak Djokovic (Serbia), Rafael Nadal (Spain) and Roger Federer (Switzerland) remain dominant at the top of the ATP rankings.

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