Ireland made it 10 successive home wins in a 28-17 victory over Argentina on Saturday at Lansdowne Road, but the win came at a cost for the Six Nations Grand Slam holders.
The hosts scored three tries to the visitors' one but lost flanker Sean O'Brien, scrum-half Kieran Marmion and centre Robbie Henshaw, who was hurt in the warm-up, to injuries.
Their losses could prove a spanner in the works for head coach Joe Schmidt's plans with world champions New Zealand due next Saturday in a clash of the top two-ranked teams in the world.
"There are lots of positives to take out of this," said Irish captain Rory Best. "It's been a long time since this group played together so rust was inevitable. With Robbie dropping out too so close to the match was also a blow."
For the Pumas, fly-half Nicolás Sánchez – whose 12 points took him to 692 Test points – landed a long range penalty in the third minute after young full-back Jordan Larmour failed to release the ball.
Ireland stormed back and such was their confidence of getting the better of the Pumas forwards Jonathan Sexton rejected going for goal on two occasions, opting for touch instead.
It nearly came off when CJ Stander went over driven on by his fellow forwards but the video referee was unable to discern whether or not he had touched down.
However, from the resulting scrum, Marmion went over from close in although Sexton sent his conversion attempt well wide of the posts.
Sánchez restored Argentina's lead with another finely-struck penalty after Ramiro Moyano took a superb catch off his own kick-off, putting the Irish in all sorts of trouble.
The hosts were all over the place just after the quarter of an hour mark as the Pumas' vibrant backline ran them ragged ending with young wing Bautista Delguy going over in the corner for his first Test try. Sánchez failed to convert leaving the visitors 11-5 up.
The hosts came back again, making merry against the Pumas scrum.
They turned the ball over and with referee Nic Berry playing advantage, centre Bundee Aki burst through off a Marmion pass breaking opposing skipper Pablo Matera's tackle to touch down. Sexton converted for 12-11.
Another Sánchez penalty – Aki being penalised – put the visitors 14-12 up as the first-half wound down.
A thriller of a half ended with Sexton landing a long range penalty .
However, joy was tempered with sadness as flanker Sean O'Brien playing his first Test for almost a year due to hip and shoulder injuries went off holding his wrist.
Sánchez put Argentina back in front early in the second-half only for Sexton to reply as the hour mark approached to give the hosts an 18-17 advantage.
Once again, though, his penalty was countered by an injury to a key player as Marmion went off limping.
The Irish finally earned some breathing space when Marmion's replacement Luke McGrath broke Matera's tackle to go over after being fed by Stander. Sexton converting to put them more than a converted try ahead.