A doubt over Atlantic Jewel's appearance in the Cox Plate and some sage words of advice from jockey Craig Newitt led to Chris Waller's backflip over starting Foreteller in the weight-for-age race.

Waller caused a sensation at Cox Plate acceptance time on Tuesday when he declared Foreteller would be a runner.

Hours earlier he indicated the horse would bypass the Moonee Valley feature in preference for the Mackinnon Stakes while indicating he was seriously considering paying up for Doncaster Mile winner Sacred Falls to run.

Back in Sydney on Wednesday for the midweek meeting on the Kensington track, Waller revealed the reasons for his change of heart.

"I was wary that Atlantic Jewel wouldn't run (because of a wet track) and might then go to the Mackinnon and that was the race we were choosing, thinking it could be a touch easier," Waller said.

"But when rain was forecast and the horse (Foreteller) worked so well in the morning, Craig Newitt said `you should run, he's got the best formlines leading into the race'."

Newitt's words resonated with Waller as he raced between venues to watch his Melbourne team of horses work, pondering what to do.

In the back of his mind was the fear he might try to dodge Atlantic Jewel in the Cox Plate, only to bump into her seven days later.

The more Waller thought about it, the more reason there seemed to run Foreteller.

"It was common sense," he said.

And indeed it has turned out that way.

Atlantic Jewel won't race in either the Cox Plate or the Mackinnon after a tendon injury was discovered following her work at Flemington on Tuesday.

She has been retired.