Nazeef made a successful leap to Listed company as she just edged out Billesdon Brook in the EBF/Unibet Snowdrop Fillies' Stakes at Kempton.
Trained by John Gosden and ridden by Jim Crowley, Nazeef won three of her starts last season but was taking a jump up in level in this mile event.
Ridden with plenty of restraint by Crowley, her stablemate Scentasia tried to do it from the front under Frankie Dettori but she was in trouble with around a furlong and a half to run.
Billesdon Brook, the 2018 1000 Guineas victor and last year's Sun Chariot scorer, looked to have the race at her mercy as she moved to the front, but Nazeef was flying down the outside for Crowley.
She swept into the lead and pulled away by three-quarters of a length, making full use of the 3lb she was getting from the winner. Outside Shepherd Market stayed on for third.
Gosden was represented by his son Thady, who said: "She didn't have the smoothest trip round and was quite far back, nothing really took her into the race and obviously the surface is riding quite slow at the moment so it was a very pleasing performance.
"They often improve as they get older and she's definitely come on well. She ran very well last year but she has strengthened and matured nicely this year. Hopefully she will continue to improve.
"We will see how she is after the race and we could possibly look at Royal Ascot with her, but it's entirely up to Sheikh Hamdan (al Maktoum, owner).
"I'm sure he'll decide what he wants to do, but possibly a tilt at something like the Duke of Cambridge (Stakes)."
Crowley added: "Obviously I didn't have a great draw. I was struggling to get into position. I shuffled back after the bend and it was a really good performance, especially on a track which has shown to be hard to win on.
"She has done nothing but improve with every run she has had in the last year and she keeps getting better and better."