NEW YORK — Sloane Stephens’ remarkably rapid rise from a ranking of 957th in early August to U.S. Open champion on Saturday began with the slow work of coming back from surgery on her left foot.

After being off tour for 11 months because of her injury, Stephens easily beat her close friend Madison Keys 6-3, 6-0 in the first Grand Slam final for both, becoming only the second unseeded woman to win the tournament in the Open era, which began in 1968.

“I mean, there is no words to describe how I got here — the process it took or anything like that,” Stephens said, “because if you told someone this story, they’d be, like, ‘That’s insane.’”

After the operation in January, Stephens couldn’t walk for a month. It wasn’t until May that she would get back onto a tennis court — and even then she was off her feet.