PARIS. If momentum counts for everything in tennis, nothing will stop Serena Williams from winning the French Open for just the second time in her career in Paris on June 8.At 31, the superstar of the women’s game is on an unprecedented winning run going in to the consecration of the claycourt season at Roland Garros.Four straight tournament wins at Miami, Charleston, Madrid and Rome (the last three coming on clay) and 22 matches in all for the loss of just four sets represents the best unbeaten streak of her career.Nothing suggests that that is about to end in Paris. And yet there are demons to be confronted for the American diva in the city she says is her favourite place in the world.Namely 11 previous campaigns and just the one championship win – in 2002 when she defeated sister Venus in the final – as the first step on the road to her famous "Serena Slam” of all four Grand Slam titles.Since then a combination of injuries, lack of focus and claycourt calamities have brought losses to the likes of Katarina Srebotnik and, most surprisingly, in last year’s first round, to France’s Virginie Razzano, which saw a frustrated Williams stomp off the Philippe Chatrier Centre Court in a decided huff.Since her 2002 triumph, amazingly she has only once managed to get past the quarterfinal stage.But, on the face of it, all that is about to change.All but down and out after missing 11 months in 2010 and 2011 with a right foot injury followed by a life-threatening pulmonary embolism, Williams has re-dedicated herself to her sport and the results have been hugely impressive.A repeat of last year’s debacle, she says is out of the question – the lesson has been learned."I was feeling excellent last year and I didn’t do great,” Williams said of her loss to Razzano."This year I feel good, too, but I’m definitely more cautious. I feel I just want to win every point and do every shot the best I can at the French Open. And I’m going to work really hard and not slack at all and do the best I can.With no Justine Henin and Kim Clijsters around, and with sister Venus a non-factor on the red dirt, the main threat to Williams would normally come from defending champion Maria Sharapova of Russia or the best of the new wave, Victoria Azarenka of Belarus.But against Sharapova, Williams is 13-2 head-to-head and against Azarenka she is 12-2. She has never lost to either on clay, although all three would say that the surface is their least preferred.So what could get in the way of a 16th Grand Slam title for Serena?Sharapova and Azarenka apart, the main challengers to Williams’ supremacy are likely to be 2011 champion Li Na of China, last year’s beaten finalist Sara Errani of Italy and possibly Samantha Stosur, if the Australian can develop her top spin attack.