Maria Sharapova withdrew from her Italian Open quarter-final with Italy's Sara Errani because of "physical problems".
Serena Williams tied her longest career winning streak with a 6-0 6-1 Rome Masters rout of Dominika Cibulkova.
Maria Sharapova eased into the third round of the Italian Open with a 6-2 6-2 win over Garbine Muguruza Blanco.
Round-up: Fourth seed Agnieszka Radwanska was knocked out of the Rome International second round by qualifier Simona Halep.
WTA rankings on Monday (last week's positions in brackets):
Serena Williams made it through to the third round of the Madrid Open with a straight-sets win over Lourdes Dominguez Lino.
The latest WTA rankings, with Maria Kirilenko up to 12th.
Round-up: Serena Williams overcame a lethargic start to her Madrid Open defence to seal a 7-6 6-1 win over Yulia Putintseva.
Top seed Marion Bartoli bowed out of the Oeiras Open in Estoril in the first round after losing 0-6 6-1 4-6 to Shuai Peng.
The latest WTA rankings, with Ana Ivanovic moving up one place.
Czech Republic's hopes of a third consecutive Fed Cup title are receding fast as Italy surged 2-0 ahead in their semi-final.
The latest WTA rankings, with Maria Kirilenko dropping one spot.
The latest WTA rankings, with Anastasia Pavlyuchenkova jumping six places into the top 20 after winning the Monterrey Open.
The latest WTA rankings, with Caroline Wozniacki dropping down a place.
WTA rankings on Monday.
US Open
Tennis
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