The filly's win was their fourth in a stakes race and followed Little Brose's win in the Group 1 Blue Diamond Stakes (1200m) at Sandown last week.
Ridden by Michael Dee, Princess Duhallow ($8.50) scored by a length from Butch Cassidy ($5) with Treasurway ($19) a half-neck away third.
J D Hayes said the win of Princess Duhallow was timely with the Melbourne Inglis Yearling Sale commencing on Sunday.
"It is always timely to have a winner in general but to have one on the eve of a sale that we purchased her out of, we're just so happy for the owners and connections," Hayes said.
"That was a very professional performance and we're very happy."
Hayes said Princess Duhallow appreciated the drop back in distance to 1000m on Saturday after her fourth-place finish when resuming over 1100m at Flemington on February 18.
She's a very fast filly and we did think that she's a 1000-metre specialist because she is so fast and brilliant," Hayes said.
"She was a little bit tardy away, so I think that's what played into the different tactic and Mick Dee summed it up so well.
"He could win on a broomstick at the moment. He really summed it up and she was strong late. We couldn't be more thrilled."
With Little Brose and Blue Diamond third placegetter Arkansaw Kid heading to Sydney for the Group 1 Golden Slipper at Rosehill on March 18, Hayes said Princess Duhallow may also head to Sydney for a lesser two-year-old race.
"We'll wait and see how she pulls-up from this," Hayes said.