Jockey Chris Symons is adamant he is on the right horse in Saturday's South Australian Derby as he chases a breakthrough Group One win.

Symons rides Shoreham in the $500,000 classic over 2500m at Morphettville and says it will mean a lot if he can land the biggest victory of his career.

"I ran second in the Sydney Cup on Saturday on Norsqui and that was a bit of a buzz," he said.

"I've always been chasing that Group One like any jockey and having spent a couple of years in South Australia as an apprentice it would mean a lot to me."

Victorian-based Symons has already enjoyed big-race success in Adelaide this year, winning the Group Two Adelaide Cup on Tasmanian stayer Norsqui.

He was narrowly denied aboard Red Colossus in the 2010 South Australian Derby when beaten a long head by Kidnapped.

Symons said he wouldn't swap Shoreham for any other horse in the field of 15 on the back of the Saab Hasan-trained gelding's impressive last start Galilee Series Final win over the same distance at Flemington.

"I reckon I've got the best horse in the race," the jockey said.

And his confidence was buoyed when Shoreham drew perfectly in barrier three.

Symons picked up the ride on Shoreham last start and was impressed by the way the stayer put 3-1/2 lengths on his nearest rival in the straight.

"I was amazed the way he showed that turn of foot after pulling so hard in the run," he said.

"I think he's a classy horse over a trip. He's proven that he'll run it out no worries."

Symons is often promoting racing in his own time and a Group One would be a fitting reward but he knows they aren't easy to win.

"Don't get me wrong, if I don't get it, so be it," he said.

"I know everyone says, `you've got to get a Group One, you've got to get a Group One' but I'm pretty grateful for what I've already done in my riding career."

Shoreham ($4.40) is being narrowly shaded for favouritism by Hvasstan ($4) with TAB fixed odds, while Hioctdane ($4.60) and Gerontius ($6) are also right in contention.