"It has been said by a few people before but it is like finding a way to beat the All Blacks, it's not easy but it's not impossible," says McGrath.
"We did it a couple of times in major races last season and we have done it before in Sales Series races up here (Auckland).
"I think you can only keep analysing what you do as a trainer and keep trying to get better.
"But of course it also comes down to what stock you have and that is why the yearling sales are so important.
"I took 16 yearlings home this year from the sales and I bought them to win Derby and Sires' Stakes races, not run second or third.
"Those yearlings are my future and my owners' future so we are in for the fight," McGrath says.
McGrath is bringing that attitude to Friday night's Derby, saying he will instruct driver Blair Orange to use Sheriff's barrier draw to try and stay in front of the All Stars pair.
"I think often if you hand up you are running for second or third at best.
"And sometimes that is fine because each horse has to be rated to its strengths.
"But I think Sheriff is good enough to try his luck and make them work."
McGrath's second-stringer, Aloka, cost punters plenty when galloping in front in a lower-grade race last Friday but the trainer is not expecting a repeat of that problem: "He is a place chance at least ..."
While Chase Auckland lost his unbeaten record to Sicario last Friday, he will open as Derby favourite, having been forced to sit parked, and should improve with the run, his first in two months.
This Derby has real depth, incredible because it is an unusual year for our elite pacing three-year-olds, with sales, sickness and exports having halved the number of stars available.
Of the 13 top juveniles who made it to the Jewels last June, only two return for Friday's Derby while Australasian Breeders Crown winner King Of Swing has been sold to Perth. So the fact Alexandra Park has been able to attract nine genuine top-class three-year-olds is surprising.
The classic is the highlight of a huge meeting, with two rich juvenile finals, the City of Auckland Free-For-All, Greenlane Trotters Cup and Northern Mares Classic making it the strongest Alexandra Park meeting for the rest of the season.
Woodlands Derby
Alex Park, 8.48pm Friday
$250,000, 2700m mobile
The field
1: Culpeka (1)
2: American Brave (2)
3: Triple Eight (3)
4: Sheriff (4)
5: Aloka (5)
6: Chase Auckland (6)
7: On The Cards (7)
8: Pat's Delight (8)
9: Sicario (1 second line)
