Chinas Zheng Saisai has progressed to the last eight at the WTA Tenerife Ladies Open after winning an epic encounter with Clara Tauson, while Zhang Shuai is into the doubles semi-finals.It took Zheng two hours and 48 minutes to overcome the Danish No 7 seed 7-6(7), 2-6, 6-4 in the Canary Islands on Thursday.Chinas No 3 singles player, who is ranked 86th in the world, next plays Colombian world No 63 Camila Osorio in the q
