Justine Henin successfully defended her WTA Tour Championship title by beating Maria Sharapova in a marathon final in Madrid.

The French and US Open champion, who has not lost since her shock defeat to Marion Bartoli at Wimbledon, won 5-7 7-5 6-3 in a match lasting three hours and 25 minutes.

Henin, who went 5-0 here en route to claiming the 39th title of her career, becomes the first repeat winner of this event since countrywoman Kim Clijsters in 2002-03.

The seven-time Grand Slam champion also had a 12-set win streak at this event heading into her match with Sharapova, who promptly ended that.

The players each traded a break early in the first set leading up to classic 12th game, with Henin was on serve trailing by a 6-5 count.

Sharapova saved three set points in the game while Henin persevered through seven set points before eventually to caving in to the Russian.

Henin was uncharacteristically poor on serve during the 70-minute first set as she double faulted six times and converted just 49% of her first serves.

The second set went with serve until the Belgian finally broke the Sharapova serve in the ninth game, having missed three opportunities earlier in the set.

Once more Sharapova broke back immediately for 5-5, but she was unable to prevent Henin from claiming a third successive break and then holding to love to level the match.

The champion then earned the first break of the deciding set before saving three break points to hold for 3-1.

Yet again, though, Sharapova came fighting back, holding serve in the fifth game and then, after receiving treatment for fatigue at the change of ends, cancelling out the break to get back on serve at 3-3.

Her energy visibly draining, Sharapova slipped 0-40 down in her next service game and although she retrieved one on those points, Henin secured the crucial break at the second time of asking.

Sharapova battled to the end, saving four championship points as the ninth game stretched out into another series of deuces, but Henin won at the fifth attempt after the Russian netted a drop shot.

Already guaranteed to finish number one in the world for the second consecutive season, the triumph gave Henin her 10th title of the season, making her the first player to reach double digits since Martina Hingis took home 12 trophies in 1997.

Despite missing the early portion of the 2007 schedule - including the Australian Open - due to the breakup of her marriage, Henin put together a career season.

She reached the final in 11 of the 14 events she played and compiled a 63-4 mark along the way.

Henin ends the season with a WTA Tour-leading 25-match winning streak - which dates back to that shock defeat by Bartoli.

Sharapova, who would not have qualified for this event if not for the withdrawal of Venus Williams, finished an otherwise disappointing season on a high note despite the loss.

Limited to 13 events due to leg injuries and persistent bursitis in her right shoulder, the former world number one earned just one title in 2007.

The 2004 champion of this event, Sharapova had gone unbeaten in four matches here before falling to Henin for the sixth time in eight meetings.

Meanwhile the doubles final was won by top-seeded Cara Black and Liezel Huber, who claimed a 5-7 6-3 10-8 victory over second seeds Ai Sugiyama and Katarina Srebotnik.