The daughter of Selkirk, who carries the colours of Sheikh Ahmed, won the Prix de l'Opera and finished second in the Breeders' Cup last season but had not run up to that level on her three starts this season.
When last seen she was third in the Blandford Stakes at The Curragh but she signalled that day that she was on the way back.
Since her return from Ireland, Roger felt that she had flourished and her work had been exceptional. For that reason he made the decision to run in the Flower Bowl at Belmont Park in New York.
She broke from stall eight under John Velazquez and he settled her in the rear along with I'm A Dreamer. The pace was not strong so Velazquez moved up into fifth at half-way.
The leaders kicked with three furlongs to run and Nahrain was the first ridden along.
However, she didnt lose ground and when she turned the final bend she found her stride and began to eat up the ground.
She forged her way between the leaders, Zagora and Dream Peace and hit the front - passing the post a good neck to the good.
Roger said: "I'm delighted to see Nahrain back to her best. She showed in Ireland last time where she ran to the line that she wasn't far off.
"I have been really pleased with her since and she has shown before that she travels very, very well. Getting her back to her has been a huge effort from every one at Kremlin.
"We shall see how she is before making a decision where we will go next but she has gained a 'win and you're in' to the Breeders' Cup Filly and Mare Turf so that would be an option."
Nahrain on the limkilns under her regular rider Iva Milickova.