Defending champion Victoria Azarenka cruised into the quarter-finals at Indian Wells with a 6-3 6-1 win over Urszula Radwanska.
The world No 2 extended her unbeaten run in 2013 to 17 matches, despite suffering with a sore ankle which she admits has her worried ahead of a quarter-final clash with Caroline Wozniacki.
The Belarusian is bidding to become the first woman to successfully defend the Indian Wells title since Martina Navratilova in 1991.
It was a bad day for the Radwanska family, with Urszula's big sister Agnieszka - the No 3 seed - also tumbling out of the tournament at the hands of Maria Kirilenko, losing 6-1 4-6 7-5.
Top seed Azarenka broke Radwanska jnr's serve three times in the opening set and twice in the second in a routine win, with her ankle troubling her more than the Pole.