Having to defy history is not something that fazes trainer Danny O'Brien.

He bucked the trend in last year's Cox Plate when he sent Shamus Award into battle as a maiden and emerged triumphant.

And it isn't worrying him heading into Saturday's Group One Newmarket Handicap (1200m) with Shamexpress who is out to become just the fifth horse, and first in more than three decades, to win the time-honoured Flemington sprint in consecutive years.

"There's always history, but you certainly don't let it scare you," O'Brien said.

"No maiden had won the Cox Plate and it didn't stop Shamus Award.

"Probably it's not often that a horse gets the opportunity to win back-to-back Newmarkets because obviously when they are handicaps it is harder to do.

"But I think we've got the horse that has made the necessary improvement and hasn't been crucified by the handicapper. So he gets every chance to do it."

The last horse to win back-to-back Newmarkets was Razor Sharp in 1982-83.

Six have tried and failed since, most recently Rubitano who finished eighth as favourite in 2003.

O'Brien can't fault Shamexpress and says the four-year-old is a better horse than last year.

He carries 4.5kg more this time around but takes in strong weight-for-age straight form with seconds in the VRC Sprint Classic and Lightning Stakes.

O'Brien has followed a proven pattern in the lead-up, giving Shamexpress an easy jump-out down the straight on Tuesday.

Shamexpress finished third in a three-horse trial behind Bernabeu and Va Pensiero.

"We just let him stretch his legs and that's usually the way we approach these straight races, particularly with him," O'Brien said.

"It's been a good formula. He just goes out and comes down on the bridle and has a blow and it usually tops him off for the race."

Shamexpress is at $4.80 behind the Mick Price-trained duo, Samaready ($3.80) and Lankan Rupee ($4.20).

But it is last year's runner-up Moment Of Change, winner of the CF Orr Stakes and Futurity Stakes at his past two starts, O'Brien rates the biggest danger.

"His two Group One wins have been nothing short of sensational and he's very good down the straight," he said.

"I think 58 (kilos) is not enough to anchor him, and he's the one I think is the one to beat."