The 15^th seed’s 6-3, 7-5 triumph at Flushing Meadows in New York means her 37-year-old opponent remains one short of equalling Margaret Court’s record of 24 Grand Slam singles titles.

Since returning to the game in September 2017 after having a daughter, Williams, who turns 38 this month, has twice reached the Wimbledon and US Open finals, only to falter at the last.

The American made a total of 33 unforced errors, while her opponent, making her debut in a main draw at a Grand Slam, totalled 17.

The multiple Grand Slam champion rallied when she was a set and 5-1 down, saving one match point and getting back to 5-5, but she could go no further.

After securing a stunning victory on her third match point, Andreescu sank onto her back.

"This year has been a dream come true," Andreescu said.

"I am beyond grateful and truly blessed.

"I've worked really hard for this moment.

"To play on this stage against Serena - a true legend of the sport - is amazing."

Williams, who has now lost successive finals to Naomi Osaka, Angelique Kerber, Simon Halep and Andreescu, was disappointed with her performance in the final.

"I believe I could have just been more Serena today," she said.

"I honestly don't think Serena showed up. 

"I have to kind of figure out how to get her to show up in Grand Slam finals.

"It's inexcusable for me to play at that level.

''All of it honestly, truly is super frustrating.

 “I'm, like, so, so close, yet so far away."