Sania Mirza failed in her bid for a second doubles title in two weeks.
The Indian ace and Yung-Jan Chan of Taipei were beaten in straight sets by Agnieszka and Urszula Radwanska of Poland in the final of the Istanbul Cup on Saturday.
The Polish sisters beat top seeds Sania and Chan 6-1, 6-3 in an hour and 10 minutes for their first WTA doubles title.
Agnieszka (18) and Urszula (16) started brilliantly, rushing into a 4-0 lead and wrapped up the first set in 29 minutes.
The best chance for the top seeds to stage a comeback was when they broke the Radwanska sisters in the fifth game of the second set to go 3-2 up. But Sania-Chan could not maintain the lead. They lost the next four games and the set 3-6.
Sania had teamed up with the United States' Vania King to win the Morocco Open doubles title last Saturday. She lost in the first round of the singles event in Istanbul to Meghann Shaughnessy.