Joe Schmidt revealed his delight at Jacob Stockdale's two-try breakthrough performance as Ireland saw off Argentina 28-19 in Dublin.
Powerhouse wing Stockdale bagged an impressive brace as Ireland eased past the Pumas, who ran in three late tries in a scoreline flattering to the tourists.
Ulster's 21-year-old Stockdale now boasts four tries in four caps, and proved his Test-match class at the Aviva Stadium.
Head coach Schmidt insisted Stockdale must still keep grafting to improve, but accepted the under-20s graduate now has the chance to launch an international career of genuine note.
"He's a kid who's learning fast, and willing to learn," Schmidt said of Stockdale.
"He's got some great athleticism, very big power and he's a young lad.
"He finished that second try really impressively, because it wasn't just the flat line, it was the fact he could arc around someone as impressive as (Joaquin) Tuculet.
"So there were some impressive aspects but at the same time he was a little bit hesitant defensively at times, and trying to win the aerial battles were a battle for him.
"He'll get some real confidence from it, I hope, but also he'll get motivation to try to improve on what he delivered tonight.
"I'm delighted with the way he's building.
"There are many aspects of his game that can help us, so it's a position that we cast the net.
"I thought Darren Sweetnam did really well last week too."
Tuculet, Juan Manuel Leguizamon and Ramiro Moyano grabbed second-half tries for Argentina, who were still well beaten despite the tight eventual scoreline.
Pumas boss Daniel Hourcade revealed his surprise at Ireland's expansive style, leaving Schmidt in turn raising an eyebrow at the visitors being caught unawares.
"I think we've always had a couple of different styles of game, so I'm surprised that Daniel said that," Schmidt said.
"He's done a super job with his team, but if he didn't anticipate what we did tonight... I'd say against South Africa (38-3 win a fortnight ago) there was quite a lot of dew on the grass, you are going to get more kicking.
"But to a fault last week we threw the ball around, against Fiji (23-20 win).
"And we want to mix our game up.
"And I think the players would agree that there's a real licence to pay.
"If the opportunity's there, play to the space.
"I don't think that's too different from what we've been doing for some time."
Full debutant James Ryan suffered a bruised shoulder, while Chris Farrell picked up a knee problem, as Ireland completed a November series clean sweep.
Hourcade felt Argentina grew into the clash, but admitted frustration at ending the year with another defeat.
"They surprised us in the way they played," Hourcade said.
"In the last two or three years they didn't play like that, and today they played a lot from their own half and wide.
"It is a style we're used to but we didn't expect Ireland to play that way. That's credit to coach Joe Schmidt."