The Pat Webster-trained Happy Clapper has twice been a Group I bridesmaid behind Winx and even with the mare in Melbourne his trainer has some concerns she may again thwart his chance in Saturday's Group I Epsom Handicap.
"The run behind Winx took a lot out of him," Webster said.
"When they run that good, you've got trouble – when horses run that good, you've got trouble reproducing it."
Happy Clapper had the crowd on their feet in the Group I George Main Stakes, giving Winx a real race down the home straight and coming within 1-1/4 lengths of causing a major boilover.
2️⃣0️⃣ in a row for the wonder mare!
— Sky Racing (@SkyRacingAU) 16 September 2017
WINX continues her remarkable win streak in the G1 George Main Stakes at #Randwick!#GoWinxpic.twitter.com/UKegN4sLUh
It was the second time that the Chris Waller-trained mare had been the difference between a feature Randwick mile win and the runner's-up cheque for Happy Clapper, with the gelding also finishing second in the 2016 Group I Doncaster Mile.
Winx is in Melbourne in preparation for the upcoming Turnbull Stakes, however there is still some concern from trainer Pat Webster that the great mare may have an impact of the result of Saturday's feature race in Syndey.
"He's going great, I'm very happy with him, so long as he can keep flying," Webster said.
"That run behind Winx, it did take a lot out of him, so we haven't done a lot with him."
Chris Waller knows that a horse needs to go to another level of exertion to challenge to his champion mare.
"I know how good Winx is, and I know she's in top form so if horses are getting close to her or if she's taking a bit to get past them then they've had a tough run, so it doesn't surprise me at all," Waller said.
"Foxplay was flat after her first-up run, she needed four weeks between runs."
In fact, each of the horses that have finished runner-up to Winx in her three starts this preparation have taken ill effects from their runs.
Foxplay missed a planned start after her Warwick Stakes performance first-up, third place-getter Ecuador has remained unplaced in two subsequent runs, while Red Excitement has subsequently failed after pushing Winx all the way in the Chelmsford Stakes.
While the trend doesn't look promising, Pat Webster believes he's done all he can to get another peak performance out of the seven-year-old.
"He's a fresh horse, that's what he likes. We've basically done nothing but kept him a happy clapper, excuse the pun," Webster said.
"It's probably his best chance to get a Group I.
"He deserves to be favourite with his form over a mile and on his last run.
"If he can produce his last run well I'll be more than happy and the others in the field will be very disappointed.
" I'll tell you if he came through last start after the race on Saturday."
Happy Clapper has been well-supported in early betting to claim his first Group I success, firming from as much as $4 into a high of $3 with CrownBet.