Top-seeded Shuai Zhang returned to the semifinals of the Hawaii Open when Vitalia Diatchenko retired in the second set of their match on Friday at Patsy T. Mink Central Oahu Regional Park.

Zhang, ranked 36th in the world, reached the singles final of last year’s inaugural tournament and advanced leading 6-2, 4-1. She will face Rebecca Peterson in today’s semifinal round of the WTA 125K Series event.

Peterson survived against Ajla Tomljanovic 7-5, 7-6 (3) in Friday’s opening match and Su Jeong Jang of Korea rolled past Miharu Imanishi 6-1, 6-3 in just under 90 minutes.

Julia Boserup continued her march through the draw by knocking off third-seeded Evgeniya Rodina 6-1, 3-6, 6-1. Boserup, the last American left in the field, edged Sara Errani on Monday, then eliminated seventh-seeded Misaki Doi in the second round on her way to today’s matchup with Jang.

Boserup and Jang meet at 2 p.m. on CORP’s Center Court, with the Zhang-Peterson match to follow. The doubles final is scheduled for 6 p.m.