2018 US Open junior champion Wang Xiyu, who scored her first Top 20 win over No.2 seed Petra Martic in the first round, and Barbara Haas will both bid for their maiden WTA quarterfinal in a first encounter with each other. Haas previously reached the Hua Hin quarterfinals in 2017, when the tournament was a 125K event, but at WTA main draw level improved to just 2-13 with her own opening win this week, while Wang's WTA main draw win-loss record is now 6-12.
Qualifier and former World No.202 Storm Sanders' singles comeback has seen the Australian rise back to World No.319 in just five tournaments so far, including the biggest title of her career at the Playford ITF W60 last October. Her first-round victory over Ulrikke Eikeri was her first WTA main draw win since she defeated Peng Shuai as a 19-year-old wildcard in her WTA debut at Hobart 2014; today, Sanders will bid for her second career Top 100 scalp (following the Peng win) against No.1 seed Elina Svitolina. In Sanders' only previous meeting with a Top 20 player, she stretched Kirsten Flipkens to a 4-6, 7-6(3), 7-6(5) scoreline before falling in the second round of Hobart 2014.
Bucharest finalist Patricia Maria Tig meets You Xiaodi for the second time in Thailand in as many weeks: Tig won 5-7, 6-3, 6-2 in the first round of last week's Nonthaburi ITF W25, going on to reach the final, where she retired against Irina Fetecau. The Romanian is bidding for her third WTA quarterfinal since returning from maternity leave last April, while You is aiming to reach her first.
No.5 seed Magda Linette advanced via retirement in her only previous encounter with Peng Shuai when the Chinese player was forced to quit trailing 5-2 in the second round of Kuala Lumpur 2017.
GSB CENTRE COURT
Barbara HAAS (AUT) vs WANG Xiyu (CHN)
Not before 4.30pm
 Magda LINETTE (POL) vs PENG Shuai (CHN)
 Elina SVITOLINA (UKR) vs [Q] Storm SANDERS (AUS)
[WC] Kateryna BONDARENKO (UKR) / Tamarine TANASUGARN (THA) vs  Eri HOZUMI (JPN) / Makoto NINOMIYA (JPN)
XUN Fang Ying (CHN) / ZHENG Saisai (CHN) vs Ankita RAINA (IND) / Rosalie VAN DER HOEK (NED)
Patricia Maria TIG (ROU) vs YOU Xiaodi (CHN)
 Arina RODIONOVA (AUS) / Storm SANDERS (AUS) vs HAN Xinyun (CHN) / Bibiane SCHOOFS (NED)