Kassia gained her first success in Listed company when she finished to good effect in the visionsport.com EBF Stallions Boadicea Fillies' Stakes at Newmarket.
With three wins to her name already this term, the Mick Channon-trained 15-2 shot, who finished fifth in last year's Queen Mary Stakes at Royal Ascot, took a step back up in class in her stride to take the six-furlong prize under Graham Lee.
Gravity Flow, who was on a five-timer, looked to have the measure of her rivals, having seemingly stolen a clear advantage on the stands' side rail entering the final quarter of a mile.
Despite the brave efforts of the William Haggas-trained runner, she could not quite hold off Kassia, with a head separating the pair at the line.
Channon said: "We just followed them into it, really. She deserved that. She is very good. We just had a little issue with the stalls which held us up a bit. That's probably why she is good now as she has taught herself.
"We always thought she was a good filly but she stays in training. She works like a very good filly.
"We will have to have a good go at all the good races. She's an out-and-out sprinter so we are in no two minds where we are going. I think next year she will be better again."
Island Vision appreciated a step back up in trip when victorious in the Dubai Business Internships Fillies' Nursery Handicap.
Having been out of luck in two outings since landing a maiden at Chelmsford, the David Simcock-trained two-year-old addressed that matter when she helped Jim Crowley move another step closer towards his first Flat jockeys' title.
As was the case in the first race, all the action came down the stands' side - despite the field having initially split into two groups.
Last-time-out Ascot winner Flying North looked set to follow up when she moved to the front approaching the two-furlong marker.
Although Timmy Murphy did get out of a response out of his mount when called on for maximum effort, it was not enough to match the finishing kick of the 11-1 winner, who moved on inside the final furlong to oblige by a length.
Simcock said: "She run very well in a good nursery at Doncaster last time out. We were slightly hoodwinked after her run at Newcastle in June where she was favourite for a nursery there. It was about the time, though, that the horses were not running great.
"She looked like she didn't get home then so we dropped her back to six (furlongs) at Doncaster and it blatantly looked like she wanted further.
"She was very strong at the line and Jim said another furlong wouldn't be a problem. We might give her one more go this season. She will get a mile. She will be a great fun filly and is progressive. There are more races in her for definite."
Coronet (3-1 favourite) and Frankie Dettori narrowly got the better of stable companion Cunco in the Godolphin Flying Start Zetland Stakes.
The filly really caught the eye in the Denford Stud silks, with connections already thinking about a potential Classic onslaught next season.
Trainer John Gosden said: "The Musidora (at York) will be the obvious place to go, but she is an Oaks filly. She has a little filling out and growing to do."
Improving filly Muffri'Ha signed off from racing in the best possible fashion with a length-and-a-half defeat of Carry On Deryck in the Godolphin Stud And Stable Staff Awards Darley Stakes.
Group One-winning colt Johannes Vermeer, having his first start for 342 days, was an honourable third.
Winning trainer William Haggas said: "She loved the fast ground and really picked up. What a game filly. I don't know who she will go to, but she deserved this."
