Justine Henin-Hardenne confirmed her status as the new world number one with victory over the deposed Amelie Mauresmo at the WTA Championships.
It is the first time Henin-Hardenne has won the end-of-season title
The Belgian, who guaranteed the top ranking with her semi-final win over Maria Sharapova, beat Mauresmo 6-4 6-3.
Neither player could dominate on serve, with nine breaks in total, but Henin-Hardenne always had the edge.
She took the first set with a rasping backhand winner and clinched victory with four breaks in the second set.
The victory in Madrid is reward for a year that has seen Henin-Hardenne reach all four Grand Slam finals, but only take the title at the French Open.
606 DEBATE: Give your thoughts on Henin-Hardenne's victory
Henin-Hardenne, 24, came into the tournament having missed nearly two months while recovering from a muscle tear in her right knee.
"You know how hard it was in the last few weeks and I didn't expect to win," she said.
"I played very aggressive and I really wanted this victory so I came out only to win it. I put a lot of pressure on every point."
She took her chances and I didn't, that's the way it is
It was against Mauresmo that she lost at both the Australian Open and Wimbledon, and the Frenchwoman also won their round-robin encounter in Shanghai on Friday.
The final was a different story, however, with Henin-Hardenne looking the more focused from the start and continuing her policy of attacking the net.
She got the better of three breaks to win the first set and took command with another at the start of the second.
However, Mauresmo broke straight back and remained up for the fight, clenching her fist determinedly after putting away one smash.
But her serve faltered too often and it was no surprise that Henin-Hardenne's victory was secured with a Mauresmo double-fault.
"It's the first time I play well in the championships, and it's not my best surface but I proved I could play here and I played well on it," said Henin-Hardenne.
"It's been an unbelievable week."
Mauresmo said: "She was better than me today. I wasn't able to produce what I did yesterday. I didn't serve the way I needed to. I was a bit tired.
"I had to give up a lot of energy to qualify for the semi-finals and yesterday against Kim (Clijsters). She took her chances and I didn't, that's the way it is."
Lisa Raymond and Samantha Stosur retained their doubles title at the WTA Championships when they came from a set down to beat Cara Black and Rennae Stubbs 3-6 6-3 6-3.
The WTA Championships will return to Madrid in 2007, WTA chief executive officer Larry Scott announced on Sunday.