Martina Hingis and Sania Mirza have now won 18 matches in a row and eight titles together this year.
Hingis said the key is that when they're faced with important points, they raise their level. In Beijing, Hingis and Mirza beat Hao-Ching Chan and Yung-Jan Chan of China in the final, 6-7(9), 6-1, 10-8.
"They dropped the level a little bit, and we were right away on top of them, broke them, were always up. I think that's what was killing them," Hingis said. "That's what we did in the past matches every time."
Hingis and Mirza began playing with each other in March, winning Indian Wells, Miami, Charleston, Wimbledon, the U.S. Open, Guangzhou, Wuhan and now Beijing.
Bethanie Mattek-Sands and Lucie Safarova won the Australian Open and the French Open. Safarova, however, has been dealing with injury and illness and was unable to play the doubles at the U.S. Open. She will return to competition in Linz next week.
Hingis and Mirza are in position to finish as the year-end No. 1 team. The duo have already qualified for the WTA Finals in Singapore. Seven teams have already qualified, including Mattek-Sands and Safarova.