Cassidy made the most of an inside barrier to guide Raiden ($16) to a neck win to Cahill's mount Intrinsic ($21) in the Tropical Fresh Plate (1110m).
Cassidy will link with Sydney trainer Chris Waller to ride Endless Drama while Cahill will venture across the Tasman to ride The Bostonian in the Group One Haunui Farm Classic (1600m) at Otaki next Saturday.
It will be a home coming for Cassidy who learned his trade in New Zealand before coming to Australia where he has ridden 43 Group One winners and won premierships in Sydney and Brisbane.
“I ride for Chris when I can and I always get reminded I was the jockey when Winx won the first of her 30 races in a row,” Cassidy said.
“Obviously to ride for Chris in a Group one is a real buzz.”
Cahill, who has ridden seven winners in the past three days, will partner Tony Pike's horse The Bostonian in the Haunui Farm.
“I won the Daybreak Lover Stakes and the Sunshine Coast Stakes on The Bostonian in the winter. I have only been to Wellington (which is near Otaki) once before so I am really looking forward to it,” Cahill said.
Newcastle trainer Kris Lees trained both Raiden and Intrinsic and it continued the good run of his Gold Coast satellite stable.
Premier trainer Tony Gollan got the third leg of a treble when Trail Of Glory ($31) beat stablemates Kittie Kins ($5) and Macewen ($2.80).
“She may have been the outsider of the three but she trialled well this week and she had luck where the others didn't,” Gollan said.
Earlier Gollan continued to sing the praises of Get Stuck In ($1.85) after he scored a last-stride win.
Gollan also won with Vincere Volare.