Allen steered the Danny O'Brien-trained Russian Camelot ($2.90 favourite) to victory in the group 1 $400,000 South Australian Derby, 2500m.

It was Allen's first ride on the Irish-bred Russian Camelot, which has won three of five starts and is being hailed as a potential big player in staying ranks for the spring.

Allen said O'Brien was confident Russian Camelot would have too much class for his Derby rivals.

"Danny said to ride him like he was the best horse in the race and he was confident if he was close enough on the corner, he would the better turn of foot," Allen said.

"It panned out that way. He was just the superior horse."

Allen made the big call to go into self isolation for 14 days in SA to allow him ride in the COVID-19 pandemic-impacted carnival.

"It is a big commitment, but it's good racing and an opportunity to hopefully ride a group 1 winner," he said leading into the carnival.

Russian Camelot completed a treble for Allen on the second of three Saturdays he is riding in Adelaide.

He also won on Game Keeper ($5.50) in the listed $100,00 Adelaide Guineas, 1600m, for Tony and Calvin McEvoy.

Allen has enjoyed a great run in this race, with him now winning it three years in a row.,

"It definitely has been good to me and I got on the right horse again this year," Allen said.

Allen and the McEvoys had earlier combined for another stakes win with Ringbolt ($26) in the group 3 SA Sires' Produce Stakes, 1400m.