Keys failed to reproduce her rip-roaring tennis in the semi-final and lost last night in straight sets in the final at Flushing Meadows – 6-3, 6-0.
Stephens’ achievement was remarkable, given she was ranked 957 in the world after undergoing surgery on her foot earlier this year.
And Keys has explained what Stephens was like after the final.
“Sloane is truly one of my favourite people and to play against her was special,” Keys said.
“I obviously didn’t play my best tennis and Sloane was very supportive.
“If I’m going to lose to anyone today, I’m glad it’s to her.”
And Keys thinks reaching the final was beyond her wildest dreams earlier in the year.
She added: “I have had a very interesting year, surgery in the middle of it.
“I have had a great team behind me and my mum up there [in the stands] has been really supportive.
“If you’d told me I’d have a finalist trophy I’d be really proud of myself.”