Agnieszka Radwanska had reached a career-high ranking of second in 2012.
Despite the defeat, Simona Halep is assured of retaining the number one spot when the rankings are updated at the end of the tournament.
Dominika Cibulkova hardly broke a sweat as she breezed past Germany's World No.31 Laura Siegmund while Caroline Wozniacki dumped Olympic champion Monica Puig out of the Sydney International
Caroline Wozniacki, a winner in Tokyo six years ago, will face either Ukrainian, Elina Svitolina, or Japan's Naomi Osaka in Sunday's Pan Pacific Open final as she goes in search of a 24th career title
Ana Konjuh, who has made it past the third round of a Grand Slam for the first time, next faces 10th-seeded Czech Karolina Pliskova in the US Open women's singles last eight
World No.1 Serena Williams eased past 52nd-ranked Yaroslava Shvedova 6-2, 6-3 in her US Open fourth round tie to record her 308th Grand Slam match win
Agnieszka Radwanska was given a wild card berth to get into the Connecticut Open, claiming her second title of 2016 and the 19th of her WTA Tour
Venus Williams, four-time gold medallist, said she was suffering with a virus after slumping to an opening round loss at 2016 Olympics
Dominika Cibulkova defeated Poland's Agnieszka Radwanska in a high-quality clash to secure her first Wimbledon quarter-final berth since 2011
Agnieszka Radwanska, who reached the Wimbledon final in 2012, overwhelmed Kateryna Kozlova 6-2, 6-1 in just over an hour Wednesday to move into the second round at the All England Club
Agnieszka Radwanska lost in the Australian Open semi-finals and crashed out in the Roland Garros fourth round. Her only title in 2016 came in Shenzhen just after Australia
Women's singles second seed Agnieszka Radwanska and sixth seed Simona Halep lost their Round of 16 matches on a rain-hit day at the French Open.
Defending champion Stan Wawrinka was stretched to five sets by Lukas Rosol in French Open Rd 1. Spanish fourth seed Garbine Muguruza came back from a set down to defeat Slovakia's Anna Karolina Schmiedlova
Top seeds Agnieszka Radwanska and Australian Open champion Angelique Kerber crashed out of the Madrid Open in the first round
Agnieszka Radwanska, the top seed, lost 4-6, 2-6 to Laura Siegemund in the semi-final of the WTA Porsche Open.
Angelique Kerber dropped in the rankings after her semifinal loss at Charleston.
Novak Djokovic had said male tennis players should earn more money than their female counterparts, considering the fact that more people watch their matches.
Serena Williams reached just her second semi-final of the Indian Wells in 15 years by beating Simona Halep 6-4, 6-3.
