Zhuhai - Sixth seed Madison Keys pulled out of the WTA Elite Trophy in China with a knee injury on Saturday.
The American was due to play Garbine Muguruza on Saturday evening at the Hengqin International Tennis Center in Zhuhai for a place in Sunday's final.
Keys, 23, will be replaced by 26-year-old Wang Qiang, who finished second in their round-robin group with Daria Kasatkina.
Julia Goerges, 30, is playing Ashleigh Barty, 22, in the other semi-final on Saturday.
Now in its fourth year the Elite Trophy features 12 players ranked roughly from nine to 20. This year's total prize money is $2.35 million across the singles and doubles tournaments.