An enforced scratching from the Magic Millions Classic, Dieters will be given a second chance to win a big two-year-old race this preparation.

On race eve, Racing Queensland vets ruled the unbeaten Dieters out of the $2 million Classic on January 9, citing leg soreness.

Sunshine Coast trainer Jason McLachlan was shattered by the decision which denied him the chance to win the race for a second time.

He and his father Bruce won the Millions with Phelan Ready in 2009 and the gelding went on to complete the big two-year-old double in the Golden Slipper.

"On Monday he could have run and won. That is the way things go but it was hard to take," McLachlan said.

Dieters has gone for a break but will be brought back with an autumn carnival campaign in mind.

"I will take him to Canberra for the Black Opal Stakes and then we will see about Sydney after that," McLachlan said.

McLachlan's father won the 1991 Black Opal with Sormani who was unplaced in the Golden Slipper won by Tierce.

"I am sure Dieters is up to the southern races and he deserves his chance," McLachlan said.

The Black Opal on March 6 has been won by some top horses in recent years including multiple Group One winner Criterion in 2012.

Criterion finished sixth in that year's Golden Slipper won by Overreach.

Canberra local, the Frank Cleary-trained Catbird in 1999, is the only horse to win the Black Opal/Slipper double.

The Clarry Conners-trained Decision Time has come closest since, running second in the 2010 Golden Slipper to Crystal Lily.