Unseeded Sloane Stephens completed a spectacular return from injury by beating fellow American Madison Keys to win the US Open at Flushing Meadows.

Stephens, ranked 83rd, beat 15th seed Keys 6-3, 6-0 in the final.

The 24-year-old was ranked as low as 957th six weeks ago, having shortly returned from 11 months out because of a foot injury incurred at Wimbledon. She becomes only the fifth unseeded woman to win a major title in the Open era.

Both women were making their Grand Slam final debuts, and their combined ranking of 99 was the lowest for a US Open final since the rankings began.

Close friends since childhood, they shared a long hug at the net after Keys netted a forehand on the third match point.

‘I had surgery in January, and if someone had told me then that I would win the US Open, I would have said it was impossible,’ said Stephens.

‘Madison is one of my best friends on tour. I wouldn’t have wanted to play anyone else. I told her that I wished it could have been a draw.’

The first American woman apart from the Williams family to win a Grand Slam singles title since Jennifer Capriati did so at the 2002 Australian Open, Stephens collected $3-million in prize money.

Over the course of 61 minutes, Keys made 30 unforced errors to just six from the rock-solid Stephens.

After the first four games went with serve quickly, Keys was broken when a forehand flew long, and a similar error gave up the set after half an hour.

Keys offered up another opportunity early in the second with a woeful backhand volley, and Stephens grabbed her chance with a rasping backhand winner followed by a cross-court forehand.

The final appeared as good as over when Keys double-faulted to fall 4-0 down, and even when she finally earned break points – three of them at 0-40 after 47 minutes – Stephens would not buckle.

There was a final flurry of resistance from Keys, but she could only find the net on match point number three, as Stephens reeled off eight games in a row.

Photo: Clive Brunskill/ Getty Images