TENNIS: Donald McRae talks to a new and effusive Mary Pierce who has come to terms with her dark past with the help of her Catholic faith

'It's all been pretty unbelievable," Mary Pierce exclaims in a radiant burst on a bleak winter afternoon in Paris as she reflects on her starring role in one of the best stories in sport last year. In overcoming a depressing stretch of injuries and, more tellingly, a far darker past in which she had suffered years of abuse from her father, Pierce lit up women's tennis in 2005 as she hauled herself into the world's top five while reaching grand slam finals in Paris and New York.

"I remember winning my semi-final at the French," she says, "as the moment when the disbelief kicked in. It seemed so phenomenal to even reach a grand slam final again that I was overwhelmed with emotion.

"I just felt so happy and so proud of myself after all the difficult times I've been through. By the time I went back on court to play Justine [ Henin-Hardenne] in the final it was a classic case of one match too far because I was physically hurting and emotionally drained. I needed a whole week to recover."

Pierce explodes with laughter at the memory. She is similarly engaging when confronted by the familiar ritual of the sporting interview and I soon get used to her effusive involvement despite my modest queries. "Wow, what a good question!" she says kindly or, "Mmmmm, that's a tough one!"

It's impossible to imagine Maria Sharapova or Serena Williams being so generous, let alone phoning me at home to find out if we should reschedule our interview for a different day in order to allow us more time - as Pierce herself chooses to do, instead of passing on the unlikely suggestion to one of her minions on tour.

It has been pointed out before that Pierce can be remarkably polite for such a high-ranking player in the hoity-toity world of professional sport. She attributes her relentless good cheer to her religious faith but something else lurks beneath the bright surface. She will turn 31 on Sunday - another cause of disbelieving mirth on her part - and the occasion will evoke a starker recollection. Seventeen years ago she made her professional debut, as a frightened teenager, in a full-fledged WTA event.

The laughter dies when I ask Pierce what she sees when she looks back at a young girl traumatised by her domineering father. "You know," she murmurs, "tennis was never my dream as a child. It was never a case that I had watched it on TV and decided that was what I wanted to do with my life. I was simply told - commanded - that this is what I would do. And so I did it to the best of my ability."

If it were not for the emotional and alleged physical abuse Jim Pierce directed against his young daughter, her rise in tennis would seem dazzling. When she was 10 her father instructed her to pick up a racket for the first time in her life. Despite this notably late start in junior tennis her natural talent, coupled with his furious ambition, was such that two years later she won the national under-12 singles title in America.

She had been born in Canada, to a French mother and an American father, but the standard was obviously much more exacting in the United States. Even after such an astonishing ascent, Jim Pierce was unsatisfied. He drove Mary harder. Within another two years, and just weeks after her 14th birthday, she began her senior pro career. "I was just following commands," she remembers. "But I felt this awful pressure to win. It was very difficult and intense but I tried so hard."

She is emphatic when asked if the pressure eased even briefly when she won a tournament. "No. My father coached me from 10 to 18 and it was always the same. The pressure to win was immense. But we're all human and you can't win every time it's just not possible. People ask if I'm glad in a way that I endured it all and came out okay on the other side, and I just say that if I had to go through it again I would just pray it would not be so very hard. But nothing in life is a coincidence. Those events led me to being the person I am today."

She barely pauses when asked to describe the darkest part of her ordeal, as a result of which she took out a restraining order against her father in 1993. "Just dealing with it daily was the worst. As a pro from 14 to 18 I lived with it every day. Four years is a very long time."

The rage of Jim Pierce was often a public spectacle. He would berate Mary before they went out to practise or after she lost a match. And, on one infamous occasion, he aimed his fury at her opponent and shouted: "Mary, kill the bitch."

He was banned from all tour events after he verbally abused a spectator at the 1993 French Open and the incident prompted the WTA to pass a new law, the "Jim Pierce Rule", which prohibits abusive conduct on the part of players, coaches or relatives.

Even having escaped her father, and winning the Australian Open in 1995 and the French in 2000, Pierce "always felt there was something missing in my life. I could win a big tournament and still be lonely and unhappy in my hotel room afterwards. Then, one day, a girl on tour told me about her faith and right away I felt that's what was missing. I was raised a Catholic but this went deeper".

She insists that, beyond a ferocious training programme, her rejuvenation on the court is rooted in this new serenity. Forgiveness has also forged a reconciliation with her father.

"Things are now great with my dad. He lives in Florida with his [ second] wife and when I'm there he'll watch me practise every day. We'll have lunch together afterwards and it's nice to have him back in my life again. We've both changed and so our whole relationship has changed. It's nothing like it was before."

It is more striking to hear Pierce's serious but wistful answer when she considers what she might have done had her father not forced her into tennis. "I would have been a paediatrician. I love kids, I'm very interested in medicine and it just seemed to be the field for me. I was real good at school and loved to study. So it would have been wonderful. But hey, at almost 31 I know I'm never going to be a paediatrician now."

She laughs her jangling laugh again. It seems free of bitterness, though she laments the fact that "at 13 we moved to France and I had to give up school and start correspondence courses. It was tennis eight hours a day".

And yet she has now discovered a late passion for the game. "I'm playing for me and last year was a big breakthrough. Once I got to Roland Garros my game became so consistent. I started beating girls I never had, like Justine [ Henin-Hardenne] on the way to the US Open final."

Currently at number five in the WTA world rankings, she welcomes the return of another old rival she previously struggled to beat. "Martina Hingis is so talented and so intelligent on court that it's going to be really interesting to see how well she does at the Australian Open [ next week]. There are about 10 girls with a realistic shot of winning. Lindsay [ Davenport] is number one but I beat her twice last year and I think Martina's big worry had been the Williams sisters because they used to dominate her physically. But no one knows what to expect from Venus and Serena - so Martina will feel that their threat is not as great."

As for Sharapova, Pierce notes that "Maria seems very quiet and closed. She doesn't hang out or talk to any of us so I've never gotten to really know her."

She responds dryly to the suggestion that Sharapova has been diverted by her glamorous endorsements. "I think she likes that stuff. But all the photo shoots and media launches add a lot of pressure. When I got that sort of attention I didn't like it. And Maria always seems so serious to me. It's kinda sad actually. It would be good to see someone that young laughing and having a lot of fun."

As a once-hounded girl who had little fun or laughter in her life, Pierce is more qualified than most to remind Sharapova of the importance of levity. And the haughty young Russiancould learn something from Pierce's exuberant anticipation of next week's Australian Open.

"I love it. Next to Roland Garros it's my favourite tournament. I love Australia. I love the people. I love the courts. And of course I go there dreaming of winning another grand slam. I'd also love to get to number one - because that's something I've never done before. I kind of feel an obligation to try to make it happen."

Pierce laughs softly again, as if she wants to make it up to that little girl who was shouted at so often, who dreamed of becoming a paediatrician but ended up, instead, as a professional tennis player who finally broke free and learned the art of happiness.