Jelena Jankovic managed to dodge the rain long enough to reach the last eight of the DFS Classic in Birmingham but Maria Sharapova was not so lucky.
Second seed Jankovic beat Maria Kirilenko 3-6 6-3 7-5, but top seed Sharapova could only complete her warm-up with before the rain came.
The Russian will now play 16-year-old Austrian Tamira Paszek on Saturday, although the forecast remains poor.
Organisers may have to extend the event to Monday or even abandon it.
Third seed Daniela Hantuchova and Eleni Daniilidou were also unable to get on court on Friday.
Jankovic said she had woken with a stiff neck on Friday morning and she was in deep trouble at a set and a break down against Kirilenko.
But the Serbian had the better of 11 breaks of serve in the match to come through a marathon third set.
"I was struggling and didn't play my best tennis but I stayed in the match and found a way to win," said Jankovic.
She is scheduled to meet Ukraine's Alona Bondarenko in the semis after the sixth seed beat American Vania King 6-1 6-3.
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