"I can't remember the last time we asked him to go hard off the gate but I realise we have to this week.
"So I will give him a brisk warm-up and get his mind on the job and I am sure he will leave pretty quickly.
"But whether that will be quick enough to hold Lenny, I don't know.
"And if he gets in front of us then he will be very hard to catch."
The pair quinellaed the Ballarat Cup last Saturday, with Smolda leading and just holding out the Victorian pacer, who was fresh up since winning the Inter Dominion sitting parked in Perth on December 13.
Lennytheshark is likely to take more improvement out of that race and has an exceptional Melton record so the first 10 strides of the race could decide it, with all other drivers on the front line certain to hand up to one of the favoured pair.
Purdon won't have any such early worries with Lazarus in the A$200,000 Victoria Derby, with the superstar three-year-old having to settle early from a second line draw before attacking.
"It is quite a good Derby with plenty of depth but I am not too worried about the draw because he is a very good horse."
If Lazarus has to sit parked he will still probably win so getting caught up in traffic three wide looks his biggest concern.
With Ohoka Punter looking way too good for the open class second stringers in the standing start feature tomorrow night it could be an epic night for the Kiwis, rounded out by Monbet in the A$50,000 Australasian Trotting Champs.
He has a 20m handicap but the final is missing series second favourite Arboe and most of the other fancies have drawn the second line, meaning Monbet should get a nice tow into the race.
Further north, Have Faith In Me and Fight For Glory will start very short in their Menangle races, with co-trainer Purdon expecting both to win.
With no Alexandra Park tonight, the domestic focus is on Addington tonight and the Invercargill Cup tomorrow.
Trots trio
Best bet: Matatoki (Addington, R2, No.3): Better for northern campaign and looks a Trot Derby horse.
Bounce back: Costa Del Magnifico (Invercargill, R9. No.1): Being off the front a huge advantage for natural leader in Invercargill Cup.
Melton best: Ohoka Punter (Melton, R6, No.5): On what should be a good night for Kiwis he looks way too good.