The 5yr-old, who looked sharp winning his first public appearance of the new season at yesterday's Ashburton trials, will be set for the Hannon Memorial on September 22.
Spankem unleashed an eye-catching burst of speed to outsprint Hannon-bound stablemates Ultimate Sniper and Chase Auckland in their 2400m handicap.
Purdon said he had been delighted with the way his Miracle Mile winner had returned from his winter spell.
''He has come back really well; we are very happy with him,'' the trainer-driver said.
Ultimate Sniper was far from disgraced when overhauled by Spankem and runner-up Clasina Maria in the last 100m of yesterday's event.
The 4yr-old was half a length and a neck behind the first two in his first public appearance since winning the New Zealand Derby in April.
Ultimate Sniper has returned in excellent condition following his battle with the knee problem which required surgery and ended his brilliant 3yr-old season.
Purdon said the 4yr-old and fourth placegetter Chase Auckland had also pleased him since returning to training.
''Ultimate Sniper had a little bit longer out than the other two.
''But, I have been very happy with the three of them. They have all been training well at home.
'''And I was happy with their efforts in the trial.''
Spankem and his two stablemates will trail again next week before heading to Oamaru for the Hannon Memorial.
Purdon and Rasmussen's remaining two New Zealand Cup nominees, Thefixer and Ashley Locaz, could also head to the trails this week.
Defending New Zealand Cup champion Thefixer could not trial this week as his fitness has slipped behind his three stablemates who stepped out yesterday.
The pacer had to be given a few easy days to recover from a hoof issue recently.
Purdon confirmed it was the same issue that dogged the 6yr-old before his epic home straight duel with Tiger Tara in last year's New Zealand Cup.
''He has just had a slight setback, but he is over that now and he should be at the trials next week, all going well.
''It's the same hoof problem, but we are a bit more advanced with our knowledge now, so we were on to it straight away.''
Former Otago trotter Oscar Bonavena looked sharp in winning the fast-class trot at yesterday's trials.
Purdon and Rasmussen gave the 4yr-old a month off over winter, rather than sending him to the Breeders Crown. That plan could pay big race dividends at the New Zealand Cup carnival.
''We gave him those last couple of runs for the Breeders Crown, but there are probably bigger things in store for him,'' Purdon said.
Oscar Bonavena powered to the line showing no signs that the knee issue that ruined his 3yr-old season was still affecting him.
Purdon said the Dominion would be the major target for the lightly-raced squaregaiter.
