A decision on whether Caulfield Cup winner Southern Speed backs up in Saturday's Cox Plate will not be made until Monday with connections of borderline horses anxiously awaiting the outcome.Trainer Leon Macdonald said the mare had come through her exertions in fine form but he would not be rushed into a Cox Plate decision.The other option for the four-year-old is to wait another week and run in the $1 million Mackinnon Stakes, a race worth $2 million less than the weight-for-age championship at

A decision on whether Caulfield Cup winner Southern Speed backs up in Saturday's Cox Plate will not be made until Monday with connections of borderline horses anxiously awaiting the outcome.

Trainer Leon Macdonald said the mare had come through her exertions in fine form but he would not be rushed into a Cox Plate decision.

The other option for the four-year-old is to wait another week and run in the $1 million Mackinnon Stakes, a race worth $2 million less than the weight-for-age championship at Moonee Valley.

The committee of the Moonee Valley Racing Club will need to exercise its powers on Tuesday morning when around 18 horses are expected to be paid up for the race which has a maximum field of 14.

"I've got mixed feelings about the Cox Plate," Macdonald said.

"You don't often get the chance to run in one but she may be better suited to the Mackinnon which gives her two weeks off.

"And long term she won't be running in next year's Caulfield Cup because she will be weighted out of it and that may be when she should be running in weight-for-age races.

"I'll talk it over with the owners and we will make a decision tomorrow."

The Caulfield Cup win was the culmination of a long range plan by the Adelaide-based Macdonald and his training partner and son-in-law Andrew Gluyas.

"It's great when things come off how you plan them," he said.

The Cox Plate (2040m) was put on Southern Speed's program in case she showed she wasn't going to stay the 2400 metres of the Caulfield Cup.

She managed the distance comfortably although she had only won as far 1400 metres before Saturday.

If all the expected horses are among the acceptances on Tuesday, those in danger of missing a start include 2007 Melbourne Cup winner Efficient and Epsom Handicap runner-up Pinker Pinker.

The club's committee has the discretion to promote horses into the field which is not a problem they have had to consider in recent years.

Southern Speed was steered to victory in the Caulfield Cup by Craig Williams who has committed to Pinker Pinker in the Cox Plate.

Caulfield Guineas winner Helmet remained the $3.50 Cox Plate favourite on Sunday ahead of New Zealand Horse of the Year Jimmy Choux ($3.80) and another kiwi Lion Tamer at $11.

Southern Speed was at $31.

Both Jimmy Choux and Helmet were given workouts at Moonee Valley last week with a large contingent of Cox Plate contenders expected at the track on Tuesday for Breakfast with the Best.

The final field will be declared after trackwork followed by the barrier draw.