It may have been an open handicap at Randwick, but Thunder Fantasy's stunning return from retirement was special for multiple Group One-winning trainer Anthony Cummings.

Thunder Fantasy carried 63kgs to win Saturday's open handicap over 1400m.

Despite starting as the $41 outsider, Thunder Fantasy was in a different class to the rest of the field.

After sitting midfield, he unleashed a stunning turn of foot to swamp His Majesty ($4.80) by half a length, with Religify ($7.50) a further half head away third.

Thunder Fantasy's last start was at Sha Tin in May 2015 after which he was retired due to injury.

With his tendon issues solved, Thunder Fantasy looks to have returned to the form which saw him rack up three Group One placings in Australia and a Group One in Hong Kong.

He has returned to racing with a view to enhancing his prospects as a stallion.

"He had a pretty successful racing season in Hong Kong and he developed some issues they couldn't deal with and they elected to retire him," trainer Anthony Cummings said.

He will get another chance at the top level in the Longines Mile at Flemington on Derby Day, three years after he ran third to Polanski in the blue riband Classic.

"He's up to that standard," Cummings said.

While bookmakers didn't give Thunder Fantasy a chance, Cummings was confident the horse was back to his old self.

"If he's there and on his game he's quick out and puts himself in the right spot," Cummings said.

"Two steps out of the gate and he was going to win.

Cummings trained the horse in the first stint of his Australian career before he was transferred to John Size in Hong Kong.