Victorian mare Platelet has posted a breakthrough Group One win in the $400,000 Robert Sangster Stakes at Morphettville on Saturday.

In a race expected to be dominated by odds-on favourite Snitzerland, Platelet ($9.50) came with a well-timed run down the centre of the track under Melbourne jockey Ben Melham.

In scoring by three quarters of a length, Platelet improved her career record to six wins and 10 placings in 17 starts for trainer Darren Weir.

Angelic Light ($17) ran home late for second with proven Group One mare Yosei ($26) also finishing off late to fill the minor placing, a long neck away.

Snitzerland, regarded as one of the best horses in Australia not to win a Group One, weakened out late after leading to the 200m.

She was sent out at $1.60 after easing from $1.55.

Winner of the Challenge Stakes and runner-up to Bel Sprinter in the Group One Galaxy in Sydney at her only two previous autumn appearances, Snitzerland offered little to the challenge of Platelet.

Jockey Dom Torneur, best known in recent seasons for his association with retired stayer Alcopop, enjoyed one of his finest moments in the saddle when Maybe Discreet won the Group One Australasian Oaks.

Trained on the track by Phillip Stokes, Maybe Discreet left her rivals without excuse in the 2000m Classic.

She raced away after hitting the front to beat Victorian fillies Grand Daughter and La Zuma.