Laura Robson earned a comfortable passage through to the second round of the WTA Guangzhou International Women's Open after her opponent retired injured in the second set.
Robson, playing in her first match since reaching the fourth round of the US Open, was leading 6-2 3-1 against Maria-Teresa Torro-Flor when the Spaniard was forced to pull out with a thigh problem.
Following her impressive run at Flushing Meadows, the 18-year-old Robson also became the British number one for the first time, replacing Heather Watson as she climbed up a place to a 74th in the world. Watson slipped three places to 75th.
In the second round in Guangzhou, Olympic mixed doubles silver medallist Robson will either play second seed Jie Zheng of China or Yung-Jan Chan of Taiwan.
Also progressing through to the second round were defending champion and fifth seed Chanelle Scheepers of South Africa, who defeated Chinese wildcard Qiang Wang 6-0 6-3.
Scheepers will next meet Serbia's Bojana Jovanovski, who eased past Hungarian Timea Babos 6-1 6-3.
In the other first-round matches Mandy Minella of Luxembourg beat France's Pauline Parmentier 7-5 3-6 6-3.