They say 2-0 is a dangerous lead in football, but if you are playing Zheng at tennis then 5-0 is the scoreline to beware. Zheng Qinwen made a daring escape from a 5-0 deficit for the second straight match, with this comeback sending her back into the U.S. Key points and original sources are listed below.

• They say 2-0 is a dangerous lead in football, but if you are playing Zheng at tennis then 5-0 is the scoreline to beware.S1

• Zheng Qinwen made a daring escape from a 5-0 deficit for the second straight match, with this comeback sending her back into the U.S. Open quarterfinalsS2