The Shackler will be opposed by stablemate Kings Deep, who will be making his first appearance since finishing fourth over the bigger fences at Te Aroha last October.
"He's had a jump-out and a point-to-point, but some of the others may be a bit sharper," Nelson said. "He's probably more of a steeplechaser now."
Zardetto will represent the team over the bigger fences in the Irvines McGregor Grant Steeplechase (4000m) following his last-start second at Hawke's Bay.
"I was very happy with his first-up effort, some of the other horses had a couple more runs than him," Nelson said.
The regally-bred Zardetto, is a son of Redoute's Choice and the group one winner Champagne, had an outing on the flat before he finished runner-up on his home track.