He was pleased with the initial hitout against a Georgian team making their debut appearance at this level, with his side running in nine tries, including seven from the backline.
"It was very successful and a really satisfying performance from a lot of points. We got through unscathed and we trusted our systems. The boys kept their attention. We had a couple of scrum resets, but it was everything we hoped to get out of the game.
"Performance-wise, obviously Mitch Jacobson stood out. He played the whole game and got man of the match and it was probably the strongest performance he's had in three years he's been playing Under 20s.
"Sam Nock also showed his class, and why he's a Super Rugby player. He just needs game time. I was very pleased with his leadership and his pass. Shaun Stevenson and Jordie Barrett had strong games as well."
Nock retains his place in the No 9 jersey, and will form a new combination with Stephen Perofeta at first five, replacing TJ Va'a who drops to the bench. Stevenson switches from fullback to the right wing to accommodate Jordan Trainor's first appearance, while Malo Tuitama completes the back three after coming on as a replacement and touching down in the opening game.
Robertson was impressed with the contribution from his bench against Georgia and will be looking for more of the same against the Irish.
"The impact off the bench is the strength of the squad: we talk about 23s not 15s. When you name a side, it's how you create a group when you play 80 minutes, the strength and power of the boys who played off the bench just created a little bit more. When the rain set in it became pretty torrential very quickly, but they finished the game well for us. We got a result, we rolled the bench with 20 minutes to go and we had plenty of subs left. That was part of the plan, so we kept the guys fresh for the next four games."
He is expecting another tough challenge against an Ireland side who squeaked home 26-25 against their Celtic cousins Wales in the first round.
"Any Irish side is strong and passionate. All the Six Nations squads are really strong, especially around set-piece, and there are some really good boys who will be a real challenge for us.
"We know their strengths around their lineout and getting down to our end of the field and putting pressure on us, so we need to mitigate this as much as we can, trust our defensive system, minimise our penalties and when we get the ball we hold on to it."
The match kicks off at 12.30am New Zealand time.
NZ Under 20s squad v Ireland:
Jordan Trainor, Shaun Stevenson, Sio Tomkinson, Jordie Barrett, Malo Tuitama, Stephen Perofeta, Sam Nock, Marino Mikaele-Tu'u, Mitch Jacobson, Luke Jacobson, Isaia Walker-Leawere, Quinten Strange, Sefo Kautai, Leni Apisai (c), Ayden Johnstone
Reserves: Asafo Aumua, Sean Paranihi, Alex Fidow, Hamish Dalzell, Dalton Papali'i, Jonathan Taumateine, TJ Va'a, Jonah Lowe
