After failing to come through in some of the biggest matches of her career, Kim Clijsters rallied to defeat fellow Belgian Justine Henin-Hardenne to win the Porsche Grand Prix and retain the number one ranking.

In a battle between the top two players on the WTA Tour, Clijsters stopped Henin-Hardenne from taking over her place atop the world rankings with a 5-7 6-4 6-2 victory in Sunday's final of the indoor event.

Clijsters had lost four of her last five meetings with Henin-Hardenne, including painful defeats in the finals of the French and US Opens.

But with Sunday's triumph, she will have a 151-point lead over her countrywoman when Monday's rankings are released.

"It's great to be still in this position," said Clijsters.

"To be number one for another week is a bonus.

"It's not something that's hugely important for me.

"I've had to work really hard to get there, and if I go down in the record books as the only player to get there and not win a grand slam, well at least I made it into the book in the first place."

The 20-year-old Clijsters, a year Henin-Hardenne's junior, became the fourth player to defend her title here.

She also tied Henin-Hardenne for the tour lead in tournament victories with seven, and has won more titles (nine) in the last 12 months than any other player.

This was the 17th tournament triumph overall for Clijsters, who earned £58,000 for her first complete win over Henin-Hardenne in a WTA Tour final.

She beat Henin-Hardenne in the championship at the Ordina Open in June, but her opponent retired in the second set with an injury.

However, it might be just a matter of time before Henin-Hardenne takes over the number one spot.

She lost only her second match since mid-July and failed to capture her 14th career title.

"Being number one wasn't my main goal - it was to win the match," said Henin-Hardenne.

"I just want to focus on doing the best that I can and finishing the year well at the (Tour) Championships."

Clijsters took over top ranking in August from Serena Williams, who won two grand slams this season but is out with a knee injury. Henin-Hardenne rallied from a break down and a set point to win the first set.

Clijsters won 13 of the first 14 points to start the second set before Henin-Hardenne won the next three games.

Clijsters broke in the eighth game with a series of devastating forehands and backhand volleys.

She was broken while serving for the set at 5-3, but took the 10th game to even the match at a set apiece.

Clijsters lost her serve to start the third set but battled back in a 12-point game.

She broke for a 4-2 lead and Henin-Hardenne did not win another point.

Clijsters closed out the match in two hours and 11 minutes with a backhand cross-court winner.

She improved to 9-6 lifetime against Henin-Hardenne with her first win in the rivalry since February.

"These are the types of matches that make tennis so much fun," said Clijsters.

"I was really enjoying the feeling of going into the third set after the first two were so close."

Henin-Hardenne said: "I was feeling physically tired at the end of the match, and it was hard to start the third set.

"It was a long match with lots of good long rallies. It's always disappointing to lose."