Paul Beshara came to Melbourne for the spring carnival with high expectations for stable star Happy Trails.

The Adelaide trainer still hopes they will be realised despite being forced to make an alteration to the eight-year-old's program for the second time in as many years.

Happy Trails will line-up in the Group One Caulfield Stakes on Saturday, six days after his luckless run in the Turnbull Stakes when he finished just over two lengths from the winner Preferment.

His Turnbull performance was a repeat of 12 months earlier when the gelding also had an interrupted passage in the straight, forcing Beshara to send him to the Caulfield Stakes on a quick back-up.

"It's a bit of deja vu. He never got a run in the Turnbull last year and he never got one this year, so I have to back him up," Beshara said.

"It hasn't been a good campaign really.

"He got held up in the Memsie the whole way, he had a bit of a hitout in the Makybe Diva but then we went back to the Turnbull again and he just didn't get a run.

"He needs a lung opener which he's not been getting and he needs the luck to change."

Happy Trails finished fifth in the Caulfield Stakes last year and the two horses who ran the quinella that day, Fawkner and Criterion, are among the eight runners in Saturday's contest.

Happy Trails is a $9.50 chance with George Main Stakes winner Kermadec the $3 favourite ahead of Fawkner at $4.50.

"The small field on Saturday should suit him," Beshara said.

"He should be sitting on the outside somewhere and be able to run home.

"It doesn't matter how good you're going, you must have that luck on your side."

Mark Zahra replaces Dwayne Dunn on Saturday with Dunn returning for the Cox Plate on October 24.

Dunn had already committed to riding the Hawkes Racing-trained Entirely Platinum in the Caulfield Stakes before Beshara's change of plans.

Beshara said the Cox Plate performance of Happy Trails would determine whether the horse pressed on to the Melbourne Cup, a race for which he has yet to qualify.