The Tony and Lynn Prendergast-trained 5yr-old has been left with just three rivals to clash with following the scratching of three of the 1840m feature's seven acceptors.
Showpin goes into the race battle-hardened after having to clash with his stablemate, Who Dares Wins, in his last start.
His solid third placing over 1600m in open handicap company at Riccarton showed his trainers he was ready.
"At Riccarton he did the donkey work and really fought on really good," Tony Prendergast said.
"Waimate is nothing like Riccarton, as far as a testing track goes.
"The turning track should suit him."
Showpin will start for the first time past 1600m from the Prendergast stable in tomorrow's $25,000 feature.
The 5yr-old had one failed attempt at a middle distance race when he began his career.
The galloper has shown vast improvement since then, and Prendergast said stepping up to 1840m should not worry the horse tomorrow.
"I don't think it will worry him.
"He is a handy little horse, but he is as game as.
"We have been really happy with him."
Should the Waimate track stay in the dead condition it has been in throughout this week, it would suit Southland raider Come Fly With Me.
The 8yr-old is one of two horses trainer Stephen Blair-Edie has among the four horses left in the Waimate Cup.
Come Fly With Me is a six-time winner on dead surfaces.
The mare has been forced to race on heavy and slow tracks in her past four starts.
Come Fly With Me gets in to the Waimate Cup with an extremely competitive 51kg weight, courtesy of Amless Bohorun's 3kg claim.
Blair-Edie will also start Wild Jack in the event.
Outsider He's Irish was the only other horse outside Showpin and the Blair-Edie duo left in the race as of yesterday.
