McDougal will leave it to Nelson to plan the rest of the winter for Argyll while the immediate plans for The Cossack are still being decided as well.
Meanwhile, a patient ride by Phelan paved the way for promising hurdler Dr Hank to deliver a feature jumping race victory when he dominated his rivals in the closing stages of the Waikato Hurdle (3200m).
"It's fantastic to win a race like this and I think this horse is a very promising jumper," trainer Harvey Wilson said.
"We were pleasantly surprised with him last year as he just kept stepping up after he won his maiden jumping start.
"This year, he really looks to have furnished nicely and we think he could be in for another good campaign," Wilson said.
"He is quite a leggy type and very nimble, so when he does make an error, he seems to be able to get himself out of trouble.
"He didn't need to do that and it was a beautiful ride by Shaun, as he bided his time on quite a testing track and put him in the race when the leaders started to come back to him.
"The Great Northern Hurdle [4200m] in September is our main target this season, so we will put together a plan to get him to that race over the next couple of months."
Dr Hank has won seven of his 39 career starts and more than $141,000.
- NZ Racing Desk