If he had wanted to, New Zealand trainer Trent Busuttin could have thrown out a decent challenge to his Australian rivals after El Roca drew perfectly in Saturday's Group One Caulfield Guineas.

The colt, who arrived in Melbourne with a reputation as one of his country's best three-year-olds, lived up to it at his only local run finishing second to Eclair Big Bang in the Guineas Prelude.

El Roca then came out at Caulfield on Tuesday and produced some of the best work of the morning when he galloped with handy older horse Dany The Fox.

And then came barrier two, a perfect gate for a front-running colt on Melbourne's best leaders' track.

But Busuttin took the cautious, Kiwi approach.

"It's no secret that the level of three-year-olds over here, especially from 1400 metres to 1600 metres, have the edge on ours in New Zealand," Busuttin said.

"He went well enough at his first start here, but he'll have to step up again on Saturday."

But it won't need to be a big step if El Roca can continue with the sort of natural improvement he has shown in each of his three runs so far, and in Tuesday's gallop.

Busuttin knows a bit about winning good races in Australia having brought Sangster here in the spring of 2011 to claim the Victoria Derby.

And he knew of El Roca's ability long before the colt stepped out on debut at Taupo in August.

"Right from day one he's shown ability," he said.

"He probably would have been among the best two-year-olds in New Zealand, but we couldn't get him to the races."

The usual juvenile issues of shin soreness and untimely growth spurts prevented El Roca from racing at two - but Busuttin has no regrets on that score.

After the Taupo maiden win El Roca stepped up to Listed company at Ruakaka for his second run and won by two lengths, confirming a trip to Melbourne.

In his only run here he led and was run down in the Guineas Prelude.

Then came the impressive training effort in which his well-performed partner couldn't go with him.

"Dany The Fox's trainer Mick Price told us he'd be a good horse to work with - if he could keep up with Dany The Fox he'd be going well."

But the situation was reversed with Dany The Fox flat out to stay within a couple of lengths of the New Zealand colt.

Busuttin could barely disguise his delight - but he tried to.

"It was good, but you need to be putting in that sort of work if you're serious about being in a Group One race," he said.

The bookies thought he was serious, trimming El Roca from $9 to $7 with only two other runners preferred ahead of him for the 1600 metre feature.