Justine Henin rallied to beat Maria Sharapova 5-7 7-5 6-3 today and win the WTA Championships in the longest three-set final in the tournament's history.

Henin won on her fifth match point, breaking Sharapova after the Russian hit a drop shot into the net. The match lasted a record three hours, 24 minutes.

"What a way to finish the season," Henin said. "It's a dream today what happened." 

Henin, who won her 25th straight match, saved five of Sharapova's six break chances in the final set – and 14 of 18 overall – to become the sixth player to defend the WTA's season-ending championship.

It was also her 10th title of 2007, making the 25-year-old Belgian the first player since Martina Hingis in 1997 to record double-digit victories in a season.

Sharapova, who came into the tournament after about a two-month lay-off due to a shoulder injury, took the first set after breaking in the 12th game on her eighth set-point.

Henin then corrected her erratic serve to secure an important break in the 11th game of the second set.

Henin ran to the crowd to hug her coach and family after winning her 38th career title. Her post-Wimbledon unbeaten run is the longest to close out a season since Steffi Graf won 38 straight after losing in the French Open final in 1989.

Henin is also the first player to win the French Open, the US Open and season-ending championships since Graf did it in 1996.

The US$1 million (A$1.08 million) prize money also means Henin surpassed Kim Clijsters to set a season earnings mark of US$5,367,086 (A$5.8 million).

Sharapova rallied in the final frame after Henin broke in the third, breaking in the sixth to even it at 3-3. But one of Sharapova's nine double-faults in the seventh gave Henin the lead for good as she held serve before taking it.

Henin improved to 21-1 against top-10 players this year.

"It's an honour to play against her," Sharapova said. "I hope we can play a few more times. I hope I can get my revenge a few more times."

Henin's win marks the end of a two-year spell for the WTA tournament in Madrid. It will be played in Doha, Qatar, through 2010 before a three-year stint in Istanbul, Turkey.