After winning 12 consecutive matches, Shahar Pe'er fell to her second straight defeat on Monday.
The 22-year-old Israeli was knocked out in the first round of the Japan's Women's Open in Osaka, losing 3-6, 6-3, 6-4 to her former doubles partner, India's Sania Mirza (61).
Pe'er, who dropped four places to number 38 in the world earlier Monday, claimed the titles in Guangzhou and Tashkent before losing in the first round in Beijing last week. She will be hoping to end her losing streak in her final tournament of the year in Luxembourg next week.
In other tennis news, Justine Henin has been granted a wild card entry to the Australian Open in what she is targeting as her comeback to Grand Slam tennis.
Henin, who won the 2004 Australian Open among her seven major singles titles, announced last month she was returning to the women's tour after more than a year in retirement.
"I spoke to Justine's team over the weekend and was happy to grant her request for a wildcard," Australian Open tournament director Craig Tiley said in a statement Monday.
"Justine is the ultimate competitor and we are looking forward to welcoming her back.
"I know Justine will not have made the decision to come out of retirement lightly, and have no doubt she will be in great shape and prepared to compete against the world's best."
The Australian Open has up to 12 wild cards to issue in each of the men's and women's 128-player draws.
Henin will not have a protected ranking when she returns to the tour and so will need to get wild card entries or enter qualifying to get places in the main draw.