Tan Tat Diamond became the scourge of bookmakers for the second time in as many starts when he continued an unbeaten run at Flemington on Saturday.

Tan Tat Diamond landed a $9 to $3.70 move in a Geelong win at his first start before the Peter Moody-trained two-year-old was backed from $7.50 to $4.60 in the Hong Kong Jockey Club Handicap (1200m) at headquarters.

Moody says Tan Tat Diamond has always shown ability but the Caulfield stable hasn't been behind the well-executed plunges.

"The backing at Geelong surprised the hell out of all of us and again today, I can tell you," Moody said.

In contrast, Black Caviar's close relation Beluga Caviar drifted from $4.40 to $11.

Beluga Caviar threatened to upset the Tan Tat Diamond support before his lack of race experience told and he wound up in the minor placing.

"He's just a kid playing at the moment and next time in we'll see the real horse I think," Beluga Caviar's jockey Dwayne Dunn said.

Tan Tat Diamond had a head to spare over the Patrick Payne-trained Raposo but Moody said the two-year-old continued to surprise him with his form so early in his career.

Moody said Tan Tat Diamond would improve with age but he would give the gelding a chance in stronger races at the end of the spring carnival.

"Is he a (Caulfield) Guineas horse? Everyone dreams of that but he might be a nice Carbine Club (Stakes) or Sandown Guineas horse at the end of the spring and he might be a nice horse in the autumn," Moody said.

The Chris Waller-trained Dupe `Em was sent out the $4 favourite but an ordinary start left him at the back of the field before he pleased jockey Craig Newitt in finishing fourth.