The world number one swept past close friend Caroline Wozniacki 6-3, 6-3 in the final to go level with Chris Evert as a six-time champion in New York yesterday.
The win also took her level with Evert and Martina Navratilova with 18 majors.
Both legends even stumped up for a gold bracelet for the 32-year-old Williams bought from Tiffany in New York to mark the occasion with '18' engraved into its single charm.
"I never thought that me, Serena Williams would be in that group. Who am I? I never thought you would mention my name with such greats and legends. I was just a kid with a dream and a racquet. Living in Compton, you know."
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The American star now has 63 tour titles while her US Open prize money fund took her on-court career earnings through the $63 million mark.
That would take her to within three of Steffi Graf's 22 and closer to Margaret Court's all-time mark of 24.
"I'm already looking at maybe No. 19. I want to continue to rise and continue to play really hard and do the best that I can."
Williams won her first US Open in 1999 as a 17-year-old and added further triumphs in 2002, 2008, 2012 and 2013.