Overreach showed just why she has dominated Golden Slipper markets for weeks with a comprehensive display at Rosehill on Saturday to give Gai Waterhouse her fifth win in the world's richest race for two-year-olds.

While Waterhouse took it all in her stride, jockey Tommy Berry was overcome by emotion as he soaked up his first win.

The filly's owner George Altomonte was more reserved, but justifiably proud as he became the first person since TJ Smith to individually breed and race the Slipper winner which the great trainer achieved in 1986 with Bounding Away.

After giving the filly the perfect run on the rails just behind the leaders from barrier one, Berry brought Overreach off the fence to the middle of the track in the straight.

She stretched out in the slow ground to hold Sidestep ($11) at bay by 1-3/4 lengths with a length to Sweet Idea ($10).

Doubts about her ability in wet ground made punters a little nervous with Overreach with as much as $3.10 bet before she was wound in to $2.80 after being $2.30 early in the week.

She covered the 1200 metres in 1:11seconds.

"She showed her superiority," Waterhouse said.

"I'm so admiring of Tommy Berry. Not only is he a capable jockey he has the ability to be able to flow with things." Berry waved to the crowd but as soon as he was greeted by his family, including his twin brother Nathan in the enclosure, the tears came.

"Nathan is the biggest part of my career," he said.

"Gai has put a lot of faith in me and so has the owner.

"Nathan and I walked the track after the BMW. Nathan convinced me there was nothing wrong with the fence around the corner."

Berry told Waterhouse he wanted to stick to the fence and she gave him carte blanche to do what he thought best with one proviso.

"You do what you like as long as you win," she told him.

The closest Altomonte has come to winning the Slipper was in 2003 when the Waterhouse-trained Hasna ran third before winning the Sires' Produce Stakes and the Champagne Stakes, with both races now on Overreach's program.

"This is by far my biggest win in racing," said Altomonte who runs Corumbene Stud at Dunedoo in western NSW.

"It is so good because I bred her and this is the pinnacle of all races," he said.

Overreach is by dual hemisphere Darley stallion Exceed And Excel who is also the sire of Sidestep and fourth-placed Guelph.

"He has done a wonderful job," Darley's Henry Plumptre said.

One-time Slipper favourite Villa Verde ($10), the only horse to have beaten Overreach, and New Zealand filly Ruud Awakening ($8.50), both went back from their wide alleys and never looked like being a threat.

Villa Verde made some ground late to finish seventh while Ruud Awakening struggled, beating just Dothraki to the line.

Criterion ($9.50) bungled the start and put in a good effort to finish sixth.

His jockey Hugh Bowman rued what might have been but was happy for Altomonte who hails from the same small country town as he does.

"It's good to see the Slipper go to Dunedoo," Bowman said.