Karolina Pliskova marked a memorable debut at the bnp Paribas wta finals Singapore, defeating Muguruza from match point down on Monday.
A couple of hours after kuznetsova came back from the brink against radwanska, Pliskova produced an even more unlikely turnaround to triumph, 6-2, 6-7(4), 7-5.
"Inside I'm still in shock that I won this one. Inside I still believed that I could win, but she was playing so well in the second and third sets," Pliskova told BT Sport after stepping off the court. "There's always a chance in tennis until it's done, so I'm really happy with the win today."
Trailing 5-2 in the final set, victory looked improbable. But Pliskova continued to go for her shots and as she did Muguruza faltered.
Pliskova will next play on Wednesday, taking on fellow comeback queen Kuznetsova.