Trainer Chris Waller has returned serve at English racing commentator Matt Chapman, saying he has shown a lack of respect for Winx and Australian racing in general.

Chapman made the comments at Tuesday's Cox Plate barrier draw function, claiming Winx's opposition during her unbeaten streak over the past 3-1/2 years had been moderate.

"I've taken those comments in and I was very, very surprised and disappointed, to the fact that I think he is a bit of a d***head for saying it really," Waller told Melbourne radio station SEN.

"You're in a foreign country, you should have a little bit of respect.

"It's a bit harsh to say that over the past three-and-a-half years where she has been winning, he is basically saying every horse she has beaten is rubbish.

"Well that just puts a mockery on Australian racing, which is regarded as close to the best in the world.

"I'm sure our punters and followers of racing will be disgusted by those comments."

Winx has beaten more than 60 individual Group One winners during her winning sequence.

Chapman also said Hugh Bowman would have to ride the mare differently and not let English visitor Benbatl get too far ahead if she was to win her fourth Cox Plate and take her Group One record to 22 and her unbeaten streak to 29.

He also challenged the international handicapping panel to rate Saturday's Champion Stakes winner at Ascot, Cracksman, as the best in the world above Winx.

"Hugh Bowman doesn't want to sit ten lengths or fifteen lengths off Benbatl, because this is one of those very strange European horses that seems to run better when he is abroad," Chapman said.

"Back home he would be nowhere near our best horses at a mile-and-a-quarter or a mile-and-a-half horses - which are Enable and Cracksman.

"And Cracksman, some of you might have seen in the Champions Stakes at the weekend.

" ... if the handicappers do their job properly he will now be the best horse in the world, if he is rated on what he did at the weekend."

The last English horse to top the world's best rankings was the incomparable Frankel in 2012.

In 2013, Australian sprinter Black Caviar shared the honour with French filly Treve; the following year Japan's Just A Way was rated the best and a year later American Pharoah from the United States was on top.

For the past two years American horse Arrogate topped the rankings ahead of Winx who was rated the best horse in the world on turf.

In 2018 she has led the rankings since the beginning of the year.