Then it changed. Safina beefed up, grew fitter, altered her entourage and for about a year, from the spring of 2008 to the summer of 2009, she was arguably the most dominant woman on the tennis circuit, even with the temper still in tow.
Safina reached three Grand Slam finals, two at the French Open, and it seemed like it was only a matter of time before she'd join her charismatic brother and become a Grand Slam champion.
But in this case, a happy ending for the much liked Safina doesn't appear to be on the horizon.
It's been five months since the Russian, who is suffering from a bad back, played a match, and from the sounds of it, her three-set loss to Julia Goerges in Madrid might have been the last encounter of her eventful career.
"To be honest, I'm not sure that I'm going to come back," the 25-year-old said in a phone interview from Germany, where her back was being examined further. "But I don't want to say officially that I'm going to retire."
Pressed further on the possibility of returning, Safina, now ranked 129th, added: "Right now when I have this back pain, I don't think [of it] at all. I'm sick of this pain."
Sometimes the pain is unbearably bad and other times it diminishes. However, it's ever-present. She revealed the diagnosis in April of last year during a three-month stint on the sidelines -- two stress fractures and a ruptured muscle.
A few weeks later, Safina was quoted as saying on her official website that she missed the "adrenaline, competition, the nerves before a match."
Now she can't even dwell on the like.
"I'm not missing it at all," Safina said. "If you live with this pain for a year and a half, it's not fun anymore. Whenever I start to think I'm going to have this back pain again, it's just frustrating. So for me, I just want to have a normal life. If one day I would like to come back, I will start to practice, but I don't want to say when, what ... I just want to live day by day."
Safina's coach since February, Davide Sanguinetti, can relate.
Sanguinetti, an Italian who possessed an unorthodox but nice looking game, was forced to call it quits because of a knee injury. His dream of competing at the 2008 Olympics, where Safina won a silver medal, never materialized.
Yet Sanguinetti was in his mid-30s at the time and already had a long career.
Safina tried to play tennis with a friend in August in her hometown of Moscow. Nothing competitive, mind you; simply a little rallying. Perhaps it could have been the building blocks to a comeback.
But after 15 minutes she had to end the session. Another MRI was taken, and Safina said it showed the fractures weren't healing, and the back was in worse shape.
"I hadn't touched a racket in a while, and I thought it was going to be fun," Safina said. "And really, my hit, it ended up not fun. Sometimes you just want to hit once a week, but unfortunately I can't even do this."
Lying in bed and sitting in planes, among other things, can be hard work, and Safina has altered her everyday movements to minimize the strain on her back. She can have a light workout at the gym to stay in shape, a far cry from the days when she put in several intense hours.
"She wants to play; she wants to train really hard," said Sanguinetti, who dubbed Safina the "sweetest person."
Indeed, Safina admitted that overplaying around this time of the season two years ago in an attempt to secure the year-end No. 1 ranking, with the back becoming more of an issue, was her "biggest mistake."
Players who've devoted their whole lives to a sport often feel unshackled when away from the game because of injury, at least initially. They take advantage of the free time to go to the movies, hang out with friends, make up for lost time.
Safina did all that. She now spends most of her time at her parents' home, taking advantage of mom Raouza's culinary skills. Safina enjoys cooking herself, and as her blogs reveal, owns a sweet tooth. Her hair color is now "dark chocolate."
"She's doing all the cooking for me now," Safina said with a laugh. "I got lazy. I said to my mom I have nothing left in the fridge anymore."
Kim Clijsters -- who handed Safina a morale-sapping double-bagel at this year's Australian Open -- Justine Henin and Martina Hingis all retired in the not-so-distant past, only to make much publicized comebacks. Although Safina hasn't officially bid adieu, seeing her on tour again, given the condition of her back, would perhaps come as a surprise.
If she is done, Safina can reflect on her career with pride.
"When I think back, what I did in a year and a half, I mean, no one could imagine me doing this," she said. "Nobody ever believed that I could be No. 1 in the world. I proved it. I did the best I could. I hope that for young girls I can be an example for them that if you work hard, you can reach everything."
London-based Ravi Ubha covers soccer and tennis for ESPN.com. You can follow him on Twitter.