The Belgian bug has really bitten. First it was Kim Clijsters, stirred by the prospect of playing under Wimbledon's roof into getting herself in shape, realising she missed the adrenalin rush of competition and, wouldn't you know it, winning the first grand-slam tournament she entered within a month of her official tennis comeback.

Now, Justine Henin, whose "retirement" from the sport was a far greater shock to everyone than Clijsters', has decided to return to the fold as well. Wonders never cease. Surely it is going to be too much to expect that the 27-year-old can play a couple of exhibitions, turn up and win the Australian Open in January, isn't it?

But the world of women's tennis has been turned upside down in a matter of weeks. Henin chose an appearance on television - she has become something of a star on the medium since putting her rackets away in May 2008 - to confirm what was first dismissed as fantasy, had begun to build into a rumour and when Clijsters chatted to me at her hotel the day after she had won the US Open the week before last, took the shape of a full blown probability. Henin is back, a quite remarkable development.

Whether it was what Clijsters achieved in New York on September 13 that tipped the balance, we can only speculate, but the seven-time grand-slam singles champion (only Wimbledon has eluded her) will be back, flashing that huge smile, those improbably beautiful backhands and displaying the enormous courage that gathered such acclaim the first time around.

"I'm very impatient, very happy and very emotional to announce that I'll be back very soon," Henin said. "This may be surprising, since my decision to quit on May 14th 2008 was a very definitive one but in the mean time I've had time to consider all parts of my life and I felt the little flame inside growing bigger and bigger. I started thinking about all the people I knew on the tennis circuit. I have been missing them. I feel the need to share a new adventure with them.

"I took the decision alone, sitting in my little corner. The decision came after a long discussion with a very close friend of mine. Carlos Rodriguez [her one and only coach] was very surprised. It took me two or three more months before I revealed to him my comeback plans. I want to be back very soon, I hope to start again in January in Australia and make 2010 a good year for me. I want to continue my career until the Olympics in London 2012.

"Many things have happened since last year. My sister gave birth to a child and I also wanted to start a family. But suddenly I felt that I'm not ready for this step. I recharged my batteries in the last 15 months and I'm ready for a comeback."

It is a stunning turn of events, every bit as a jolt as her decision to step away in the first place. Stacey Allaster, the chairman and CEO of the Sony Ericsson WTA Tour, was amazed. "Justine is one of the great champions in the history of women's tennis, and we, along with millions of her fans around the globe, are thrilled with her announcement," Allaster said. "She is that rare athlete who decided to step away from the game at the height of her powers, and no doubt she will be a force to be reckoned with from the get go. Her career was marked by so many amazing moments - and a new chapter begins today."

Well, not quite today, but very soon. Henin intends to play in a couple of exhibition matches to see if her game is in decent shape but the intention to return with a bang at the start of next year is clear from her comments. In May of 2008, she said her decision to retire - the first woman ever to quit while No 1 in the world - was the end of a child's dream. "I leave with my head held high," she said.

I wrote then: "The loss of Henin is immeasurable. Her style was unique, her resolution in the face of physical and spiritual adversity stunning, she possessed a power that baffled so many, given her diminutive stature, and yet this was the glory of the ponytailed waif - how she took on and defeated those who ought to have devoured her. It was very much a case of her art imitating life."

Well, now she is back and may be shinier than ever. Who can tell. Tennis is agog. We all are.