The performances prove there is promise beyond Willis. The 1500m has a pedigree in New Zealand Olympic history with Sir John Walker, Sir Peter Snell and Jack Lovelock earning gold medals.
"All three [of the contemporary trio] are likely to get the qualifying time, so it's potentially a nightmare for the selectors," Willis told Radio Sport. "Who will they pick? We've got four of the 13 fastest [1500m] runners in New Zealand history in action.
"Fortunately, I've already got my qualifying time, and I was the pace-maker for theirs, so they can't be complaining at me," he quipped.
Willis said they had emulated training guru Arthur Lydiard's coaching philosophy recently with a series of grinding workouts.
"I've been mentored and guided by my coach [Ron Warhurst] and older senior athletes, so I picked up on that with these younger guys.
"It's exciting but you can also feel the tension as we get closer to deadline. They're trying to help each other but realise they could be about to knock each other out."
Willis said it would be advantageous to have extra black singlets in Rio.
"It can be intimidating on your own. Imagine if one All Black had to do his pre-test warm-up in the locker room with the Wallabies. That's what it's like for me sometimes."