Pennino continued the family tradition of springing major upsets in black-type races when she won the Group Three Gold Coast Guineas.

Trained by Darryl Hansen, Pennino ($11) won the Guineas in a slogging finish by a length from Defence Missile ($10) with rank outsider Million ($71) a short neck away third.

The filly is by renowned wet -rack sire Easy Rocking and is a sister to Balboa Rocks who won the Sunshine Coast Cup on Australia Day at $91.

While Pennino started one of the outsiders in the Guineas, Hansen was quietly confident she would prove highly competitive.

"She's won on a heavy track previously and even though a few of the others fell by the wayside I was pretty sure she would handle it," Hansen said.

"I've always had a good opinion of her. She's been placed at Group Three and Listed level and now is a Group Three winner in her own right."

Hansen will let the dust settle before outlining winter carnival plans for Pennino.

"I was hoping to get her into the Queensland Oaks at one stage but things didn't quite go to plan so I had to change course with her and head this way," he said.

"Where we go to from here I'm not really sure. There's the Queensland Guineas to consider and I don't think she'll have any trouble with the mile.

"Her older brother Balboa Rocks has won twice over 1800 metres but there's no need to rush into anything at this stage."

Boomsara, the $2.25 favourite, struggled to handle the heavy conditions in the straight and weakened to finish last.

The Guineas changed complexion dramatically when pre-race odds-on favourite Zoustyle was scratched by trainer Tony Gollan when the track was downgraded to a Heavy 9.