Championship-winning rider Zac Purton must choose between Group One rides in Dubai and Japan after partnering Super Jockey to a dirt track win at Sha Tin on Sunday, which secured a place in the US$2 million Golden Shaheen on March 28.

With Purton's regular ride Aerovelocity a confirmed starter in the Group One Takamatsunomiya Kinen at Chukyo less than 24 hours after the dirt race in the United Arab Emirates, the Australian jockey had hoped that a late-night flight from Dubai to Osaka or Tokyo would allow him to ride in both races.

But the time difference between and race schedules would make it seemingly impossible to take both rides, with strict prerace restrictions on jockeys in Japan another hurdle.

This leaves Purton with a tough decision. "They are both very good horses with winning chances, but we will leave any decision for as long as we can," Purton said. "Obviously, I would like to ride in both races, but it doesn't look like we can do it."

Purton won the Group One Hong Kong Sprint on Aerovelocity before he was a narrow second to Gold-Fun in last month's Chairman's Sprint Prize, but riding the Paul O'Sullivan-trained five-year-old in Japan would also result in him missing a full day of rides at Sha Tin.

Jockeys at the Dubai World Cup meeting, depending on which race they are in, can usually return to Sha Tin to take rides in the latter half of the card.

Meanwhile, last year's Golden Shaheen winner Sterling City has been retired by trainer John Moore, but will continue to race under David Hayes in Australia after a long spell.

Sterling City has been unplaced in nine runs since winning the 1,200m sprint at Meydan, and finished last, beaten seven lengths, in the Class One won by Super Jockey on Sunday.

In other news, Douglas Whyte has been booked to ride Tony McEvoy-trained Alpine Eagle in the Group One Australian Guineas at Flemington on Saturday.

Alpine Eagle turned heads with a barnstorming victory in last Saturday's Autumn Classic over 1,800m at Caulfield, and was elevated to second favourite for the three-year-old mile feature.

He is one of two Hong Kong-based jockeys riding in Melbourne, with Nash Rawiller booked on favourite Kermadec, a winner over the course and distance in the Group Three Carbine Club Stakes in November.

Purton will also be in Australia, reuniting with Doncaster Mile winner Sacred Falls in the Canterbury Stakes at Randwick.