Holt, who now meets the leading Russian, Elena Timina, had to contain a patient recovery by Regenwetter in the third game, during which she spent more of the rallies manoeuvring to reduce the frequency of Holt's top-spin attacks.
the versatile Lancastrian ended the revival with a fine spell of serving in the fourth game, in which she went from 11-9 to 16-9.
The first Englishman to reach the last 16 was Alan Cooke, who beat Masahiro Hashimoto, of Japan.
Later there was a double setback when England's two leading players withdrew through injury. Chen Xinhua has a pulled thigh and Matthew Syed has a shoulder strain.Reuse content