Initially frustrated by a swirling wind at Arthur Ashe Stadium and shaken by Azarenka's second set comeback from 4-1 down, Williams regained the momentum in the third set with her power and range of strokes propelling her to a 17th Grand Slam title.
Williams will be 32 later this month but she seems far from even contemplating life after tennis.
"I feel great. I have never felt better. I feel really fit," she said. "I can play a tournament like this, singles, doubles, with tough, tough schedules. For the most part, I felt really good.
"I haven't felt like this in a number of years. I'm excited about the possibilities. I don't know what can happen. I just keep playing and do the best that I can."
Certainly Azarenka, who put up a brave fight throughout and looks easily the most likely to take over Williams' mantle whenever she does retire, had no doubts about the qualities of her opponent.
"She's a champion, and she knows how to repeat that. She knows what it takes to get there," said the Belarusian.
"I think it's incredible what she's achieving. She's playing definitely her best tennis right now. It is just really exciting for me to be able to compete against that type of player who can be the greatest of all time."
The 17th Slam victory puts Williams on a par with Roger Federer among contemporary players of both genders and brings her within one title of Martina Navratilova and Chris Evert, the fourth most successful women of all-time.
"It's an honour to be even with Roger," said Williams, "He's been such a great champion throughout the years, and he's just an unbelievable competitor and he's still playing, and he can probably still win more. ...
"He's just been so incredibly consistent, so we have had really different careers," Williams said.
"Then to be compared with Chrissy and Martina - not yet, because I'm still not quite there yet. I can't necessarily compare myself to them, because, you know, numbers-wise they're still greater."
But while she is willing to contemplate history, she is less fond of thinking about what all her success has brought her.
Williams picked up $3.6 million in prize money for her win combined with her bonus from securing the U.S. Open Series of events, which took her past the $50 million mark in career prize money.
"I don't play tennis for the money. I honestly love to play. I love Grand Slams," she said. "When I grew up playing tennis in Compton, I just never thought about any of this. I didn't even know all this came with everything.
"I think my dad got me into tennis because of the money, but me being naive and silly, I never thought about it."
Winning was always the aim, she said.
"I wanted to do what (sister) Venus does. I want to win and I want to do more and I want to do more," Williams said.
"To this day I have never ever picked up a check in my life. I remember back in the day before wiring they used to mail it because I just would forget it.
"Someone told me today I passed 50 (million), but half of that goes to my Uncle Sam. I love him. I'm always giving him half my money," she said with a smile.
What Williams does appreciate though is her ability to have been a winner at Arthur Ashe Stadium from the age of 17 to 31.
"I have won this tournament over three decades, '90s, the 2000s, and this one. You can only do that when you're younger and older, so I'm happy that I have had this opportunity."
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