Tommy Berry masterminded the end of Golden Slipper favourite She Will Reign's unbeaten record by guiding Frolic into the $3.5-million spectacle for two-year-old's at Rosehill on March 18.

Berry carried out a tactical masterclass and showed his rival hoops the best way forward during a sodden Randwick Guineas Day as he piloted Frolic ($11.70) to the outside running rail to win the Group Two $300,000 Reisling Stakes (1200m) by 2-1/4 lengths.

She Will Reign, who eased to $3.40 from $2.80 in the Slipper market, looked on track for a fourth straight victory in the first on Saturday until Frolic stormed home down the grandstand lane.

"As you know I walk the track every time I come out here. I walked it today and it was noticeably better out wide," Berry explained.

"I spoke to (trainer) Michael (Freedman) about doing it before the race and he left it up to me. I told the stewards what we we're thinking of doing just in case there was a problem and she got beaten."

That was never likely once the filly swung wide at the turn to negate a heavy 9.

"So soon as she got on the ground she quickened." Berry said.

Freedman confirmed he was happy to go with Berry's instincts.

"He said 'I think the outside fence is the best place to be'. I said if you haven't got to do too much work to get out there it's your call.

"Until she got to that part of the track she looked as though she might have been labouring a little bit, which is understandable in this sort of ground. As soon as she got that slightly better going she sprinted quickly."

Freedman was rapt to qualify Frolic, who won the restricted Inglis Classic in her last start at Randwick on February 13, for the Slipper despite atrocious conditions.

"I think she's had a perfect prep going into the Slipper and now she's gained a start she's got a nice two weeks.

"Obviously the conditions aren't ideal. There's probably a few that'll come out of it with hard luck stories because of the track," Freedman said.

She Will Reign's trainer Gary Portelli is hoping for sounder footing in the Slipper.

"I thought she was getting through it but I didn't think she was really handling it," he said, satisfied to hit the line 4-3/4 lengths clear of Villa Carlotta.

"She beat the others pretty well, We'll just look after her between now and the Slipper and hopefully we get a better track."