With ad scoring back in the mix, the first set lasted over an hour - an hour and five minutes to be exact - and it was Hsieh and Peng who squeaked it out, fighting off a set point with Hsieh serving at 5-6 and eventually taking the set in a tie-break as Petrova double faulted on their own first set point.
After trading breaks early in the second set it was all Hsieh and Peng, who reeled off four games in a row from 2-all to close it out. The No.2-seeded Taiwanese-Chinese duo moved on through, 76(5) 62.
"It's very special for us," Hsieh said. "We're best friends and we've been playing together since 10 years ago. I'm very happy we've been doing well together and that we could win our first match here."
"We're not sure who are next opponents are yet, but we'll see later, and then we'll start preparing for tomorrow," Peng said. "We're really looking forward to it and hopefully we'll be ready for them."
Regardless of which team they will face in the final on Sunday, Hsieh and Peng have to feel good about their chances - not only have they won eight WTA doubles titles together, but they are actually a perfect 8-0 in WTA doubles finals together. They won one title in 2008 (Bali), three titles in 2009 (Sydney, Rome and Beijing) and four so far this year (Rome, Wimbledon, Cincinnati and Guangzhou).
By contrast, they are far from perfect in WTA doubles finals with other partners - Hsieh is 5-5 in WTA doubles finals with other partners, while Peng is 3-3 in WTA doubles finals with other partners.
Peng and Hsieh are looking for the second-biggest title of their careers, together and individually, after both of them captured their first Grand Slam title at Wimbledon this year. That win was historic for Hsieh - she was the first player from Chinese Taipei ever to win a Grand Slam title of any kind.
And now both Hsieh and Peng are the first players from Chinese Taipei and China ever to reach the doubles final of the TEB BNP Paribas WTA Championships - Istanbul. They are only the second and third Asian players to do it - Japan's Ai Sugiyama was a runner-up here twice (in 2003 and 2007).