Australian racing continues to stem the tide of promising horses heading offshore with the owners of Brandenburg knocking back lucrative international offers.

While Randwick Guineas winner Shadow Hero has been sold to Hong Kong, the connections of Brandenburg join those of stakes winners Kinane and Front Page to turn down overseas buyers.

The news Brandenburg will continue his career in Australia is music to the ears of trainer John Sargent who believes the three-year-old's best racing is still ahead.

The colt has already compiled a strong resume, winning the Group Two Hobartville Stakes and placing against older horses in the Group One Doncaster Mile.

He is back in training at Sargent's Randwick stable and has progressed to three-quarter pace work ahead of an ambitious spring.

Sargent confirmed Brandenburg would have two barrier trials before resuming in the Group One Winx Stakes (1400m) at Randwick in August.

"He's matured now. He was always a weak three-year-old, now he's got a neck and a behind and he's strong," Sargent said.

"He should measure up with the big boys."

While Brandenburg's return race is set in stone, all options for the remainder of the spring are on the table.

The colt is yet to be tested beyond a mile but Sargent, a prolific trainer of stayers and middle-distance gallopers, has no doubt Brandenburg can extend his brilliance to longer journeys.

He has earmarked the $7.5 million Golden Eagle (1500m) at Rosehill on October 31 and the 100th edition of the Cox Plate (2040m) at Moonee Valley a week earlier as prominent targets.