But Wozniacki held out in the end, hitting the victor down Williams' right flank after the American had approached the net, before tossing her racket in victory.
"Venus Williams is a great champion and she made it very, very hard for me".
Wozniacki said the key to her victory was the pressure on Williams' serve.
"I knew she was stepping it up, she had nothing to lose at that point and she really went for it. Things were going in for her".
"Well, I can say that it's a great feeling that I can finish the year number one", Halep said after it was confirmed she would remain as number one until the start of 2018. "I just went out there and I just did my best".
But it was eventually just too much for Williams, with an unforced error count of 32 to eight against her proving telling in the end.
Williams countered with 31 winners and a first-serve percentage of 70 percent but was unable to close out service games when she needed to at the end of both sets.
"Eight is my lucky number so I was hoping if I was going to beat her at least once in my career it would be today", Wozniacki said. "I'll try to play a little better earlier next time".
With a hefty trophy perched next to her as she faced the media late last night, questions about gunning for a maiden Grand Slam title inevitably came up for Wozniacki.
The crowd wanted more but Wozniacki was not prepared to comply with their demands, breaking again to seal victory on her second match point with a backhand victor down the line and tossing her racket in the air as she celebrated a stunning win. "That might be a good plan".
During the season, Halep has reached five finals; winning the Madrid title, while losing at Roland Garros to Latvian Jelena Ostapenko, Rome against Svitolina, Cincinnati versus Spanish Garbiñe Muguruza and Beijing Open to French Caroline Garcia.
"Going into the tournament, you know that it's going to be a tough one", Wozniacki said.
Said Wozniacki, who was still shaking from the weight of the moment as she basked in the adulation of former greats and fans: "I'm really proud of how I have played all week and how I have fought and how I really produced some great fighting out there".
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