Sania in quarterfinals of Family Circle Cup WTA event
Sania, who made it to the main draw through the qualifying rounds, beat the German wild card entrant 6-4 6-4 in the second round singles match of the USD 721,000 prize money clay court event.
She will now meet 11th seed Shuai Peng of China in the quarterfinals. Peng had upset seventh seed Russian Nadia Petrova 6-3 5-7 6-2 in another second round match.
Sania has also reached the quarterfinals in the doubles with her partner Elena Vesnina of Russia.
The unseeded Indo-Russian duo had pulled off a big upset by ousting second seeds and strong contenders Liezel Huber and Lisa Raymonds with a straight-set win in the first round.
In the doubles quarter-finals, they will take on the Russian-Australian combination of Alla Kudryavtseva and Anastasia Rodionova.