India's Sania Mirza and Zimbabwe's Cara Black entered the final of the WTA China Open, shocking top seeds Sara Errani and Roberta Vinci of Italy 6-4, 6-4 on Friday.

In beating the world No 1 Italian pair, which made it to the final of five of the last eight Grand Slams and won three of them, they extended their unbeaten run to eight matches, and Sania put herself in line for her fifth title of the season.

Sania, who will be playing in her sixth WTA final this year, is having a fine season despite playing with a non-regular partner.

She began the season with Bethanie-Mattek Sands; together they won the Dubai and Brisbane tournaments, but with the American preferring to focus in singles, she teamed with four new partners -- Liezel Huber of the United States, Italy's Flavia Pennetta, China's Jie Zheng and Cara.

The Hyderabadi reached the US Open semis and won the New Haven event with Zheng before emerging triumphant at the Pan Pacific Tokyo Open with Cara. 

There were five breaks of serve in the opening set, which lasted 37 minutes, the Indo-Zimbabwean pair breaking thrice.

In the second set, Errani's serve was broken in the eighth game. But leading 5-3, Sania was unable to hold and the Italians made it 4-5.

Errani-Vinci led 30-15, but just when it appeared as if they would level the scores 5-5, a volley from Black made it 30-all. The Indian ace then hit a forehand cross-court winner to bring up match-point before a lob from Black clinched the issue after 36 minutes.

They will meet Vera Dushevina of Russia and Arantxa Parra Santonja of Spain, who beat China's Su-Wei Hsieh and Shuai Peng 3-6, 6-1, 10-8 in the other semi-final.

Image: Sania Mirza (right) and Cara Black

Photograph: Atsushi Tomura/Getty Images