MADRID, Nov 5: Serena Williams is determined to accelerate her revival into one of the great comebacks by challenging for the title at the year-end WTA Championships which starts here on Tuesday.

The former holder of all four Grand Slams seemed headed for such a comeback when she started 2007 by winning the Australian Open, fully two years since last contesting any final. That made her the lowest-ranked player to win a Grand Slam title in nearly 30 years.

Serena was then at 81 in the world; now she is up to five. But her year stalled with injuries to her groin, knee, calf, and thumb, damaging her chances at Wimbledon and causing her to miss four American hard court events later in the summer.

Although she made a partial recovery in two European tournaments, she then suffered a thigh problem while losing last month’s Moscow final to Elena Dementieva, something Serena claims will not hinder her in the coming week.

“Can you believe I played my third event in a row?” the injury-prone star asked, referring to a three-week sequence in Stuttgart, Moscow and Zurich. “I don’t believe I have ever done that in my career. I am determined to make good at the end of the year,” she insisted, and few doubt that she can – but only if all the ailments have receded.

Perhaps only Serena herself and maybe one or two physios know whether she is genuinely fit enough to capitalise on her having qualified for the year-end event a fourth time.

If she is, the world’s best known player will still have to contend with one of the strongest ever fields, even though it will be without elder sister Venus Williams.

Following the dizziness Venus suffered at the US Open in September, she took a series of tests, plus follow-up tests after tournaments in Asia. The doctors’ conclusions were inconclusive.

They felt, apparently, yet more tests were needed. So Venus decided to take a break.

“The accumulation of matches has taken its toll,” the Wimbledon champion said. “I have received several medical opinions to delay my return to competitive tennis.”

A different view of a long-lasting ailment has been taken by Maria Sharapova. The former world number one has decided to compete in Madrid despite a shoulder problem from which she has been suffering most of the year.

Sharapova’s first match in almost six weeks ended in a straight-set defeat to Victoria Azarenka of Belarus in last month’s Kremlin Cup in Moscow; it was also only her first match since a loss to another 18-year-old, Agnieszka Radwanska of Poland, in the US Open third round in September.

“This has been a very frustrating year for me physically, but I am a big competitor and I am determined to compete at the Championships,” Sharapova said.

But the real front runner for the tour climax title is the holder Justine Henin, who will be presented with the year-end world number one award before the tournament begins.

For a player who started the tour six weeks late and in despair after the break-up of her marriage to Pierre-Yves Hardenne, this is a remarkable achievement.

Henin has won the French and US Opens, taking her total of grand Slam titles to seven, and the 182,000 dollars she received for winning the Zurich tournament a fortnight ago raised her season earnings so far to 4,367,086 million dollars, the second highest in WTA Tour history.The Belgian is also certain to be sixth equal on the all-time list of world number ones with a total of 98 weeks at the top by the time the 2008 season starts.

All the stats therefore say she should win the title.

But there are two obvious threats. One is Serena regaining the form which enabled her to save a match point and defeat Henin in the Miami final back in April. The other is tiredness. Henin has played a lot of tennis.

“I need to recover now and take a few days off to be with my family and friends,” she said after winning in Zurich. “I’ve always been getting to the semis and finals of tournaments this year, so the weeks are very long for me.”

This is arguably the toughest tournament to win, because the best players oppose each other from the start. But Henin also claims it is her favourite event.

To what extent she still feels that at the end of the week will depend very much on how well the outstanding player of the year has been able to recoup her energy. —AFP