Conor Murray will be "firing on all cylinders" if he makes his first appearance of the season against New Zealand, according to Iain Henderson.
Scrum-half Murray has not played since injuring his neck on Ireland's summer tour of Australia, but could yet face the All Blacks in Dublin on Saturday.
Ireland omitted Murray from their 42-man autumn Test squad, but boss Joe Schmidt has now admitted that was mainly to not put undue pressure on the Lions half-back to return this month.
Now though, Ireland lock Henderson insists Murray can return in peak condition and form if pressed into service at the Aviva Stadium this weekend.
"If Conor were to come back in, I have no doubt in my mind that he would be back firing on all cylinders if he steps back in to play," said Henderson.
"But we just have to wait and see how his fitness is, how he slots back in to the training regime.
"And if that's going to happen, brilliant, but if it doesn't, we've got three scrum-halves there, any of whom will step up to the challenge if selected."
Ireland ground past Argentina 28-17 in Dublin on Saturday, spluttering into life in a bid to kickstart their autumn schedule proper.
Schmidt's men had swatted aside Italy 54-7 in Chicago the previous week, but in truth that was a second-string sent into action with at least one eye on long-term development.
Kiwi boss Schmidt rolled out all his frontline players to take on the Pumas, but the hosts produced a ring-rusty showing against Mario Ledesma's obdurate Argentina.
Back-to-back world champions New Zealand may only have edged out England 16-15 at Twickenham on Saturday, but the relentless rain proved a genuine leveller on the west London fare.
Sean O'Brien broke his arm during his first Test match in 12 months against Argentina, and will miss the hugely-anticipated All Blacks encounter.
Robbie Henshaw tweaked a hamstring and was withdrawn in the warm-up against the Pumas, while Bundee Aki and Kieran Marmion also wound up with minor niggles.
Aki and scrum-halves Marmion and Luke McGrath bagged Ireland's tries, with Will Addison making a reasonable fist of his full debut as a last-minute replacement for Henshaw in the centres.
Munster star Murray would doubtless boost Ireland's rhythm and tactical kicking if he steps in against New Zealand though, but Ulster lock Henderson believes Schmidt's men are well covered for all eventualities.
"Murray has been a massive part of our game over the last few years, he's a quality player," said Henderson.
"But Kieran Marmion and Luke McGrath have both stepped in and done a great job, with both scoring tries.
"We have quality players there, and they all know how to play the game we want to play. Joe has full confidence in all of them as well."