Marsha began her second season in a handicap race over six furlongs at Newmarket Racecourse on 14 May in which she carried 126 pounds and finished second, beaten half a length by Show Stealer.

Ridden by Paul Mulrennan she pulled hard in the early stages before taking the lead inside the final furlong and winning "very readily" by two and a half length from Fine Blend.

Just Glamorous set the pace before giving way to Mecca's Angel 300 metres from the finish at which point Marsha, who had been settled in mid-division, began to make rapid progress.

[9] On her first run of 2017, Marsha, as a Group 1 winner, was required to carry a seven-pound weight penalty in the Palace House Stakes at Newmarket on 6 May and started the 8/1 fourth choice in the betting behind Washington, D.C., Priceless and Muthmir.

[10] In the King's Stand Stakes at Royal Ascot in June Marsha started favourite, but proved no match for the American filly Lady Aurelia, who won easily, and lost second place by a head to Profitable.

Marsha was expected to return to winning form in the Sapphire Stakes at the Curragh in July and started the 1/2 favourite, but after taking the lead a furlong out she was caught on the line and beaten a short head by the eight-year-old gelding Caspian Prince.

Lady Aurelia (ridden by Frankie Dettori) was made the odds-on favourite ahead of Battaash, while the other runners included Profitable, Washington DC, Priceless, Take Cover, Cotai Glory and Goldream.

Dettori celebrated his presumed victory by punching the air and waving his whip to the crowd but the judge's decision was that Marsha had prevailed by a nose.

On her final racecourse appearance, the filly was sent to the United States to contest the Breeders' Cup Turf Sprint at Del Mar Racetrack on 4 November and finished sixth of the twelve runners behind the 40/1 outsider Stormy Liberal.