"If you look at the Avondale Guineas you might think we can't beat Dragon Leap and I don't know whether we can yet either," says Marsh, who sits second on the national premiership.
"But what we also don't know is whether the favourites will run out a hard 2400m. You never know that until they do but I am confident my horse will.
"I am sure he will get closer than he did last start because the Avondale Guineas was run so slowly and he kept coming whereas this week I am pretty sure they will go harder this week.
"If that is the case I think it will suit horses like our fella and Sherwood Forest. Maybe the favourites will still be too sharp but I am not convinced yet."
Marsh and plenty of his rival trainers expect a stronger tempo this week because everybody has seen the same thing in the last month: if they wait for the two favourites they will get smashed.
The problem may be that Dragon Leap has the raw speed of a top class galloper and the genetics to suggest he will run the Derby trip while Two Illicit will probably revel in a brutal 2400m.
She galloped 2:1.6 for 2000m winning the Waikato Guineas three weeks ago, a time almost as fast as the weight-for-age horses in the Herbie Dyke.
She might just be a very special filly and Dragon Leap's talent is also undisputed, so Scorpz and co might have found themselves in a very tough Derby.
Marsh is realistic but unfazed.
"I think he [Scorpz] might prove to be a Cups horse, a really good horse."
The best chance of seeing that tempo, which may or may not undo the favourites, would seem to lie with the Andrew Campbell-trained trio led by Peloton rolling forward to put some speed into the race.
The market for the Derby tightened a touch yesterday after Two Illicit drew what appears to be a better barrier at five than Dragon Leap's 12 but both have the right riders to find a path to the top of the straight that will allow a fair fight.
Marsh is also not concerned by Scorpz's former rider Jason Waddell choosing Dragon Leap as his Derby mount.
"I am not surprised, Jason was offered the ride on a $2 chance in a Derby and of course he was probably going to take that.
"That is part of the business we are in."