After being robbed of her main autumn goal, Guelph has claimed a well-deserved Group One win and will now look for a second.
Trainer Peter Snowden had tagged Guelph as his No.1 Blue Diamond prospect on the strength of some sparkling early-season form.
After an impressive Prelude win at Caulfield, she almost fell at the start of the Diamond and could do no better than ninth.
But in a tribute to her toughness, Guelph then endured a Golden Slipper preparation, finishing fourth to Overreach, and on Saturday won the Group One Sires' Produce Stakes (1400m).
Snowden will now look to the Champagne Stakes at Randwick in two weeks as Guelph's season finale.
"She deserves her chance, and she is so tough she can handle it," Snowden said.
"She's a great eater and she doesn't knock herself around on the training track.
"Everything is saved for raceday."
From her outside barrier in the 13-runner field, Guelph dropped out to the tail and then eased her way into the race from the 600m.
As the odds-on favourite Overreach surrendered to Scandiva inside the 200m, Kerrin McEvoy produced Guelph with a perfectly-timed run to swamp the leaders.
Guelph ($9.50) was eased down on the line to score by three-quarters of a length from Scandiva ($71) with Overreach ($1.35) a further half length away in third.
McEvoy added his weight to the push toward a Champagne Stakes run, describing Guelph as a "dream filly".
"Whatever you ask her she tries to do it," he said.
"She's got a great attitude and the ability to match."
The Sires' win also proved a family triumph with Guelph's mother Camarilla having won the race in 2007.
It also added to the outstanding season being put together by her sire Exceed And Excel, which has now added the Sires' to the Golden Slipper win of Overreach and feature race wins of Safeguard, which won Saturday's Kindergarten Stakes as well as English Group One winner Excelebration.