Earlier this year Peng became the first player from China ever to hold a World No.1 ranking in tennis, male or female, singles or doubles, and now Hsieh will achieve the same feat for Chinese Taipei.
"It is a great accomplishment for Hsieh Su-Wei to join Peng Shuai as co-World No.1s," Stacey Allaster, the Chairman & CEO of the WTA, said of Thursday's exciting announcement. "Not only are Hsieh and Peng a great doubles team, but they are an inspiration to the fans throughout the Asia-Pacific region."
"Reaching No.1 in the world is a great feeling," Hsieh said. "We have been working really hard as a team. I was very proud of Peng reached No.1 earlier this year and now I am happy we can share it."
"Our goal this year is to reach Singapore," Peng said. "It is nice to share the No.1 ranking with Su-Wei and we look forward to playing together the rest of the year, trying to reach the WTA Championships."
Hsieh and Peng have won seven WTA doubles titles together over the last 12 months, including two this year at Doha and Indian Wells. They have 11 WTA doubles titles together and are 11-0 in finals.
They are currently No.5 on the Road To Singapore leaderboard - the journey to the BNP Paribas WTA Championships Singapore presented by SC Global - and could go high as No.2 after Madrid.
But what's certain is they will be the 10th team ever to become co-World No.1s in doubles:
Lisa Raymond & Rennae Stubbs (3 weeks)
Virginia Ruano Pascual & Paola Suárez (3 weeks)
Lisa Raymond & Samantha Stosur (39 weeks)
Cara Black & Liezel Huber (127 weeks)
Venus Williams & Serena Williams (8 weeks)
Gisela Dulko & Flavia Pennetta (7 weeks)
Kveta Peschke & Katarina Srebotnik (10 weeks)
Liezel Huber & Lisa Raymond (20 weeks)
Sara Errani & Roberta Vinci (42 weeks)
Hsieh Su-Wei & Peng Shuai (starts next week)
Read more about Hsieh and Peng in their doubles profile page right here on wtatennis.com.