Ireland opened their Nations Championship campaign with a 42-12 bonus-point win over Argentina at Lansdowne Road, but coach Andy Farrell was quick to identify room for improvement as a blockbuster clash with South Africa looms in a fortnight.

Hugo Keenan scored a hat-trick — his first home Test in over a year — as Ireland crossed for six tries against a Pumas side that struggled for cohesion throughout. Despite the 30-point margin, Farrell said the performance fell short of what his team is capable of.

"How we can be a little bit more ruthless — that's the team that we want to be," said Farrell, who had publicly questioned Ireland's World Cup credentials in his pre-match build-up. He stopped short of repeating that assessment after the final whistle, describing the team's current position as "a good place to be".

Keenan, modest about his contribution, credited the team structure for his tries. "Three walk-ins, I think. So I'll take any, to be honest. But we got a bonus point playing against a really tough Argentinian side, to beat them by 30 points and probably not play to our full potential is exciting because there's a lot to work on."

Tadhg Beirne echoed the sentiment, acknowledging that while some of the tries were quality team efforts, the overall execution left points on the table. "There was certainly a lot of parts that need to be better."

Argentina coach Felipe Contepomi attributed much of the gulf to limited preparation time — his squad had just four days together before the Test — and an error-riddled individual performance from his players. "It's tough when you defend too much against a team that is very good with ball in hand," he said, while praising his players' attitude under the circumstances.

Ireland host Fiji next Saturday before South Africa arrive at Lansdowne Road the following week, with finals weekend scheduled at Twickenham. Argentina face Italy and then France in the remainder of their Nations Championship programme.