Group One winners Happy Trails and Go Indy Go will kick off their spring campaigns in the Group Three Spring Stakes at Morphetville on Saturday.

Both horses are being aimed at the W.S. Cox Plate and for Happy Trails it's a case of hoping he can win it on his fourth attempt - after going close to Adelaide last year and running a half-head second to Shamus Award in 2013.

Trainer Paul Beshara also has Happy Trails nominated for the Melbourne Cup and won't rule out the two-mile event, even though the horse has never raced over further than the 2040m at Moonee Valley.

"He seems a bit more dour this time," Beshara said.

"You don't really know whether he'll get the two miles until you try, but usually 80 per cent of the field haven't run over that distance."

Beshara said the heavy track at Morphetville on Saturday won't suit the eight-year-old, but the race will be an important hit out before he tackles the Group One Memsie Stakes at Caulfield on August 29.

The wet track also presents an obstacle for the Leon Macdonald and Andrew Gluyas-trained mare Go Indy Go.

"She really has to run to start off her campaign but a heavy track is not ideal," Macdonald said.

"She handles it but she hasn't raced for a year so, it's a big ask.

"She trialled well with Happy Trails last week although I thought he went better than her."

Macdonald said he expected the four-year-old to race in the Penny Edition Stakes at Morphetville before going to Melbourne for the spring carnival.

Beshara said his other runner, Group Two winner Richie's Vibe, will appreciate the give in the ground in the 1200m weight-for-age contest.

"He loves the wet and he should take up a nice position," he said.