"But at least I know if we scratch her now the final field punters will get their money back."
As an extra precaution Ritchie has left Zurella in the Lowland Stakes at Hastings on Saturday in case the Auckland weather turns feral, although that looks increasingly unlikely.
As good as Zurella was winning the Sir Tristram Classic at Te Rapa last start Ritchie knows she is going to need to produce something special to down Derby hot favourite Silent Achiever.
"She has the double James factor, with Roger training and James riding.
"That is going to be pretty hard to beat no matter how well she goes because you could hardly have a better combination for a Derby."
But Zurella has the all important Zabeel factor and being by the champion sire has given Ritchie some leeway to train her differently from her rivals.
Zurella stunned clock watchers and even Ritchie himself with a sub 60-second last 1000m gallop on Tuesday, her final 600m in 34.6, confirming she is at her peak.
"That did surprise me but I have been training her for speed more so than getting distance into her legs.
"The way I look at it, Silent Achiever is the one to beat and she has a dynamic sprint so to beat her we need plenty of speed at the business end as well, otherwise she will just out-kick us.
"So I have been working her short trips, nothing more than 1200m, to keep her sharp and I am hoping that the fact she is by Zabeel will help her get the trip without the long miles."
As if Ritchie didn't have enough to think about heading into the Derby he has to cater for Zurella's mental frailties, which he sums up simply.
"She can be a real bitch. For that reason we want to keep her as calm as possible before the race," he said.
"So I have spoken to the officials and it looks like we can come into the back parade ring late, do one lap and then head straight out on to the track.
"I think that is fair on her but also the other horses in the race, because the last thing their trainers want is a horse going mad before the biggest race of the year."
Ritchie hopes new jockey Jason Waddell will help in that regard.
"He is a strong jockey but a kind jockey so I think we have the right man for the job."
Zurella will be on the inside of a power trio drawn in the middle of the field, with Silent Achiever at barrier eight and Rock 'n' Pop at nine.
Star colt Ocean Park has drawn four but Shuka will start from barrier 16, with Angelology at three and fellow late entry Chicharita at 11.
While the Derby dominates Ellerslie's first day of Auckland Cup Week, the Nathans provides an interesting rehearsal for next Wednesday's Auckland Cup when defending champion Titch, and stablemate of Angelology, meets fellow Central Districts galloper the favourite Shez Sinsational, with only 0.5kgs between them in the handicaps.
And the unluckiest group one campaigner of the summer, Durham Town, returns to his favourite track as equal topweight in the feature sprint the 1200m Darley Plate, adding to a stellar book of rides for James McDonald.
