"She's definitely one of my favourites. I probably haven't won as many races on a single horse as her."
Her draw on the second line could work out in her favour, as she starts behind Master Lavros.
"She's actually quite nicely drawn in behind the good ones.
"She's a sit-sprint sort of a horse, so she'll obviously be able to sit in the whole way and we can see what she's made of in the finish."
Considering Miss Pegasus will be taking on open-class performers like Stent and Escapee, Williamson said a top-five finish is probably her best possible result - although Williamson has steered home a long-shot winner before in the Kurow and Waimate cups with Motu Speedy Star.
"A top-five finish would be a great effort for her.
"Seeing the class of the field, some of them are the best horses in the country. If she can even get close to that calibre of horse, she's gone a huge race."
Williamson can dig for a jewel again on Sunday when he teams up with Monnay in the 5-year-old ruby for his father. Monnay impressed against the pacers at the Oamaru trials on May 15.
"We were really happy with him - he got out of the gate good, and ran a 2:00 [mile rate] - he's pretty forward for it all."