A cramp-ridden Caroline Wozniacki lay twisted and tortured on the hardcourt of Doha in October 2009 but 12 months later she is certain to leave the same venue as the year-end world number one.

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What a difference a year makes.

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A year older, wiser and stronger, Wozniacki has been transformed into one of the most powerful players in women's tennis, a fearsome baseline brawler with the lungs and heart to run her opponents into the ground.

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Completion of this metamorphosis came on Thursday when the 20-year-old Dane sealed the year-end number one ranking by beating Italian Francesca Schiavone at the $4.55 million season-ending tournament in the Qatari capital.

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"Last year I came into this tournament a little bit injured. I think that made my body work a little bit harder for everything," Wozniacki told reporters after her 3-6, 6-1, 6-1 win over Schiavone at the Khalifa Tennis Complex.

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"This year I feel like I'm fit, I'm feeling well, feeling good physically. I've been working really hard off the court as well and that's paid off. I'm really happy about that."

Dubbed the 'Little Princess' back home, Wozniacki endured a three-hour battle against Victoria Azarenka in her opening game last year, then went the distance with Vera Zvonareva in a match that yielded blood, sweat and tears.

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After the Russian's nose started to ooze blood in the second set, Wozniacki was pole-axed by cramp in her heavily-strapped left thigh and was barely able to hobble to the net to shake hands after her three-set win.

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The Dane would later retire with an abdominal strain after the first set of her semi-final against Serena Williams.

There would be no such injury problems for Wozniacki this year, however, as the beaming blonde celebrated ending the year as the world's top-ranked player.

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The tears of last season have been replaced by steely eyes, iron will and canary-yellow nail polish.

"I've had a great season. I've played some good matches here and now I can end the year at No. 1 it's a really great feeling," said Wozniacki.

"I'm only the 10th one to finish the year as No. 1 so I'm really proud of what I've achieved."

Wozniacki, the youngest player in the Doha field, has won six titles this season and claimed the number one ranking earlier this month after reaching the quarter-finals of the China Open.

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While some have questioned her right to be crowned world number one without winning a grand slam, Wozniacki knows there will always be sceptics no matter what she does.

"For me the most important thing is I know I've had a great season," she said.

"I've won six tournaments so far and my friends and family are the ones that mean the most to me. That's what I care about."

Wozniacki needed two wins at the $4.55 million tournament in the Qatari capital to ensure she could not be caught at the top of the rankings by Russian Zvonareva.

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After blowing away Dementieva in her group opener, the Dane suffered a shock defeat to Stosur on Wednesday to give Zvonareva hope. However, the 20-year-old made no mistake against Schiavone.

"Francesca was playing really good in the first set and I didn't have too many chances to break her," said Wozniacki in a court-side interview.

"I just hung in there and kept my focus, tried to get a little more aggressive and not let her dictate the game in the second and third."

Wozniacki was delighted to finish the year as the world's top player.

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"That's something I've dreamed about since I was a little girl," she beamed.

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"I'm really happy and proud of what I've achieved this year."