Irankunda, 20, was dynamic as a winger playing off Mohamed Toure in Australia's opening 2-0 win over Turkey, then came off the bench as a striker for the second half of the 2-0 loss to the US.
But coach Tony Popovic threw Irankunda straight into the fray ahead of Toure, and Australia claimed a 0-0 draw on Thursday (Friday AEST) that sealed second place in Group D and progression to the round of 32.
"I had no idea. It was kind of like last minute for me," Irankunda said.
"But you know, we've got how many nines - Mo, Tete (Yengi).
"So it was a bit of a surprise for me when I got told I was going to be starting up front as a nine, and I didn't expect it.
"But playing for the country, I always have to try my best and play my heart out."
Largely playing as a back-to-goal striker, Irankunda battled manfully throughout, working hard to compete in the air while showing flashes of the elusiveness and running power that makes him so dangerous out wide.
Popovic wouldn't go into detail on why he made six changes but gave some insight into the different qualities Irankunda offered at the point of his attack.
"He's a different type of nine and we just felt today that he could offer something, which he did," Popovic said.
Popovic hailed how his young squad "dominated" a Paraguay team who are difficult to score against.
"You don't expect a lot of chances, but when they come you have to try and take them," he said.
"And I thought Nestor played a real part today in our performance and how we, well I say win – winning for me that we went through. So, delighted."
Irankunda relished building more of a connection with Cristian Volpato, who played on the right and linked up beautifully with the dominant Jordan Bos at Levi's Stadium.
"Me and Christian, in training every time we've been trying some combinations, and throughout the week, we've done some really good combinations," Irankunda said.
"It was unfortunate today that we didn't get that chance, because how deep Paraguay played.
"But I feel like there's still, more to see, especially from Christian's side of things - very talented player, and I feel like he's he's done very well today.
"... Hopefully he can keep showing the country what he can do."
Irankunda is adamant the Socceroos can keep working through the gears, starting in Dallas on July 3.
"There's still plenty more to come, especially with the way that we've worked the last two months," Irankunda said.
"We've worked so hard the last two months and I feel like the nation's going to see a better side to us.
"We're only going to get better from here."
11°C