"She is a good filly but has been racing on wet tracks and getting to a dry track this weekend will really help her," he said.
"She hasn't raced for a month but we see her as a real Oaks filly, so because of that, going into the 1600m slightly fresh suits her.
"Her work suggests she will be really hard to beat."
Key has a touch of class but this race should tell us more about the emerging threats in the 3-year-old fillies' ranks, with one of the more interesting being Force Of Will. She was stunning beating older horses last start and should be suited by the long straight, so it wouldn't surprise to see her overcame barrier 13.
Earlier on the card, the Benner-Wynyard stable have Hold The Press trying to remain unbeaten in race two, with the draw the major concern.
"She trialled up super recently and she can definitely win but I'd love to see her get across them and be able to lead," said Benner.
"She is very fast, but from a wide barrier, if she gets trapped out there, it gets tricky.
"So the quicker she can cross them, the better chance she has."
Hold The Press scooted over the 1000m of that recent trial win in 58.9s, beating talented older horses, and has been solid at $2.70 since she opened with the bookies.