Gai Waterhouse and training partner Adrian Bott stole the show early on Melbourne Cup day.

After Invincible Star won the opening race at Flemington on Tuesday, Sort After followed suit under Stephen Baster in the TAB.com.au Trophy.

Taken to the lead by Baster, Sort After ($3.70) shot clear soon after straightening to record a three length win from Metaphorical ($10) with Amarela ($12) 1-3/4 lengths away third.

Sort After was making her Melbourne debut and was stepping up in distance from 1400m to 1700m on Tuesday.

Bott said Sort After was among nominations for the Matriarch Stakes (2000m) at Flemington on Saturday.

"If she pulls up well and we're happy with her she'll run again on Saturday," Bott said.

Baster was struggling to remember his last winner for Waterhouse in the city area, suggesting Aqua D'Amore in the 2007 Futurity Stakes at Caulfield may have been his last.

"I haven't been riding for her too much lately but I give her a hand riding work at carnival time," Baster said.

"I've probably ridden a few winners on country tracks for her, so it's good to get another one in town."

Baster said the rise to 2000m, if Sort After backs up on Saturday, won't pose any problem for the daughter of Wanted.