Ireland will count the cost of suspected concussion to Gordon D'Arcy, Conor Murray, Rob Kearney and Jonathan Sexton.
D'Arcy's head-down charge, Conor Murray's accidental knee from Quade Cooper and the friendly fire head clash between Kearney and Sexton left Ireland open to exploitation at the death.
"They were pulled off for assessment," said Defence Coach Les Kiss.
"They'll go through their protocols (after) 24 hours, (after) 48 hours and go through the processes."
Ireland showed how far they have come since falling to New Zealand in the same circumstances last November, their defence holding firm.
That was the price for putting their heads on the block, one for which their clubs could pay the highest price as The Champions Cup looms back into sight in two weeks.
In the long-term, these four will be absolutely key to Ireland defending their Six Nations title.
"It makes a big statement if you can Grand Slam," said Rory Best.
"For us, it is about trying to improve in those five games and making sure all the hard work we've done over the 12 months with Joe is the bedrock of going forward."