MELBOURNE Oct 31 AAP - On the fifth anniversary of Rebel Raider's Victoria Derby win, trainer Leon Macdonald returns to Flemington with a horse he once believed could give him another.

But DNA testing confirmed Essay Raider was in fact a sprinter not a stayer and Macdonald had to adjust his mindset and the horse's training.

Essay Raider runs in Saturday's Group Two Yellowglen Stakes down the straight 1200m on the back of a confidence boosting win at Morphettville by 6-1/4 lengths.

"I always thought he was a stayer because his breeding suggested that," Macdonald said.

"I sent a blood sample to an Irish laboratory and the CC (comparison chart) test said he was definitely a sprinter.

"I decided on the test because every time we tried him over ground his form tapered off. He has only ever performed up to 1200 metres."

Essay Raider is by Bernadini out of Elegant Eagle, a Zabeel mare Macdonald trained to win over 2600m.

His family ties also include 2001 Golden Slipper winner Ha Ha and the Macdonald-trained 2007 Thousand Guineas winner Southern Speed.

Macdonald, who operates in partnership with his son-in-law Andrew Gluyas, believes straight-track racing should suit Essay Raider who has had a tendency to wander on the turns.

"Even his last start when he won so well, he got a bit lost on the turn so I am keen to see him on the straight," Macdonald said.

Macdonald has no regrets about missing the Victoria Derby with Geelong Classic winner Gamblin' Guru who beat Tupac Amaru in the Listed 2200m race last week.

A close relation to the Macdonald-trained 1998 Australian Derby winner Gold Guru, Gamblin' Guru will be aimed at that race in the autumn.

"He is much too immature for a Derby at this stage," Macdonald said.

"He needs more time and I'm sure it's the right decision."