A gelding competing for a major racing and breeding operation is primed to upstage a number of top-line colts in the `stallion making' Caulfield Guineas on Saturday.

And even though race favourite Long John has no future at stud, the son of Darley stallion Street Cry still has plenty to race for in the Group One feature for three-year-olds.

"We still stand the stallion and that's a credit in itself if he can win for him," Darley's Melbourne stable foreman Paul Snowden said.

The Peter Snowden-trained Long John was an eye-catching performer in the Guineas Prelude (1400m) last start, powering home for third to Eclair Big Bang and El Roca.

Paul Snowden says he's "as confident as you can be" going into the race with a horse he believes is the one to beat.

"I think he's given us a lot of confidence with the way he's presented himself each time he's gone around and how he's handled himself," Snowden said.

"I wouldn't swap him for anything in the race."

Long John was unbeaten from three starts as a juvenile in races below the top level and has returned this campaign with placings in the McKenzie Stakes first-up and the Guineas Prelude third-up. In between the two he was a resounding winner of the Listed Henry Bucks Stakes.

Snowden said the decision to geld Long John was made early when he showed signs being a colt would be detrimental to his racing.

"He was a very heavy horse as a young horse and very immature leg-wise," he said.

"If we left him a colt he wouldn't be running on Saturday, I don't think."

Long John will jump from barrier one which could be a concern if he was locked away on the fence or the ground deteriorated by the final event on the 10-race program, but Snowden believes the gelding has the ability to make his own luck.

Long John is the $4 favourite ahead of Prince Harada at $4.80 with New Zealand visitor El Roca on the third line at $7.50.

El Roca and Prince Harada are two colts Snowden pinpointed as potential dangers in an open race with plenty of chances.

"But I really think that our bloke is going to be right on song on Saturday," he said.

Long John is one of two Darley-owned three-year-olds, along with star filly Guelph, still among Cox Plate nominations.