Tennis players are creatures of habit and control. Whether it's specific pre-match routines, using the same shower stall after every match, or changing racquets every time a fresh can of balls is used, elite athletes want - nay, need - things to be exactly how they want them. 

And then there's Hsieh Su-Wei, who does not even notice if she's playing with a broken string.

"She's so precise the way she plays," Hsieh's long-time coach Paul McNamee told reporters in Melbourne, where Hsieh advanced to her first major quarterfinal by defeating Marketa Vondrousova 6-4, 6-2 in the Round of 16 at the Australian Open. "No one can redirect traffic as well as she can on both sides. Doesn't matter which way it's coming from, she can redirect it either way.

"Players change racquets on the change of balls, right? She'll go years with the same racquet."

"She was playing a match in Eastbourne one day. She missed two balls in a row by three meters. Change ends, keeps going. She's missing balls by so far. That's not Su-Wei. She misses by millimeters normally.

"I noticed she was playing with broken strings in her racquet, literally playing with broken strings. She hadn't broken a string for three years. You tell me a player that uses the same racquet for three years and doesn't change the racquet. 

"We had a bit of trauma before this tournament because she had to get a restring before the tournament. That's once a year. Players change racquets on the change of balls, right? She'll go years with the same racquet.

"She didn't know what it was like to play with a broken string, so she didn't know it was broken. One of the reasons is she hits the ball so purely in the center of the racquet. Most people break strings when they hit it around the frame. 

"She doesn't frame balls. I mean, she would rather not play if she did that."

With wins over Tsvetana Pironkova, Bianca Andreescu, Sara Errani, and Marketa Vondrousova, Hsieh became the oldest woman in the Open Era to make a first major quarterfinal. It's a remarkable achievement for a Hsieh, who already sits at World No.1 on the doubles circuit. 

"To think she's 35 years of age, in her first Grand Slam quarterfinal," McNamee said. "She's been in the Round of 16 a few times, won three WTA singles titles." 

"I always believed she had a Grand Slam quarter at least in her, quarter or a semis. That's what I felt like. She's achieved that now. She ticked that box."

McNamee knows something special when he sees it. The former ATP player and experienced coach and tennis administrator knew Hsieh Su-Wei was a special talent, even when she was ranked outside the Top 300 and struggling to build a consistent career on the WTA Tour.

"Like most people, I enjoyed watching her play," McNamee said. "I felt like that she had the potential to have the best finishing volleys in the world. In the end, she was able to achieve that. It's borne out by [the fact] she's the current No. 1 ranked player in doubles. 

"I said to her, I think you got the best finishing volleys in the world. She looked at me like I could have had two heads. She was very humble, very far removed from that. She was ranked over 300 in singles, 40 something in doubles."

The talent was obvious ever since Hsieh made her professional debut at 16-years-old in 2001. Playing on the ITF Circuit, Hsieh won her first 37 matches and winning five consecutive titles as a qualifier. 

Hsieh's road to the WTA Tour was a circuitous one. Coached by her father growing up, Hsieh stopped playing tennis for nearly a year before moving to Japan for three years to give herself more structure and support to pursue her tennis career.

But it wasn't until Hsieh linked up with McNamee that her career took off. Hsieh credits the Aussie for teaching her the ropes of the tour and opening her up to the cosmopolitan delights of living as a permanent traveler.

"Before I worked with him, I have a lot of time alone, so I don't have much information from other people," Hsieh said. "So I have no idea where is my game. That's why it is not easy to improve or to find a way out.

"Sometimes I go to the tournament, I have no one to warm up [with]. I'm more worried about how you going to survive today for the match, I hope I don't play really bad on the court because I couldn't warm up."

"She's a free spirit. You don't want to box that spirit. You got to let it rise and be free. That's the important thing. It's important that she's allowed to express herself. That's the same with her tennis."

For McNamee, the key to helping Hsieh was to simply let Su-Wei be Su-Wei, and be there when the opportunity arose to offer any advice and support.

"She's a free spirit," McNamee said. "You don't want to box that spirit. You got to let it rise and be free. That's the important thing."

"It's important that she's allowed to express herself. That's the same with her tennis. It kind of reflects the way she is off the court. She kind of acts on a whim sometimes, doesn't like to plan too far ahead. 

"Even finding out if I'm going to be helping her or coaching her, I normally only find out a week or two before," he said, laughing.

"There's only one Su-Wei. There are times when she's kind of focused and other times when she really is not motivated at all to practice. I've experienced it where she'll just go and hit one or two balls, didn't hit them well, that's it, she won't play anymore that day. Wasn't feeling it.

"The hard thing for me was I was kind of super professional. I worked hard. I would warm down with a file-mile run, that was the warm-down. She'd never been on a run."

McNamee credits Hsieh's boyfriend Frederic Aniere, who has stepped in on coaching duties over the last few years, for helping Hsieh continue to reach new heights. 

"It's nice of her to give me some credit, but really Fred has been the one that's helped her actually be more professional, if I can say that," McNamee said. 

"They live together in Paris. She likes Paris. Fred has been an amazing influence on Su-Wei the last few years. It's a team effort absolutely."