Brian O'Driscoll has beaten a stomach bug and been passed fit to feature for Ireland in their crunch Six Nations clash with England on Saturday.
O'Driscoll is part of an unchanged starting XV selected by head coach Joe Schmidt as the Irish go in search of a Triple Crown, following their easy wins over Scotland and Wales.
The Twickenham match is even bigger for the veteran centre as he will equal George Gregan's world record of 139 international caps, a mark he should own by himself by the end of the tournament.
It will be O'Driscoll's 131st appearance for Ireland, with eight Lions caps taking him level with Australia scrum-half Gregan.
Schmidt's only two changes come among the replacements with lock Iain Henderson coming in for Dan Tuohy, who broke his arm against Wales.
Leinster flanker Jordi Murphy is preferred to Munster's Tommy O'Donnell as well, and he will make a senior international debut if coming off the bench.
Schmidt revealed that O'Driscoll could have trained on Tuesday, but that the Ireland coaches took every precaution to ensure he would be fit to face England.
"Brian trained fully on Thursday, and in fact he could have trained on Tuesday, but he just was still feeling the after effects of an illness," he said.
"And with his experience and know-how he's in a good position to know what he needs, and he brought that to bear. He's fully ready to go now though."
Captain Paul O'Connell said Ireland are keeping their feet on the ground as they prepare for the challenge of beating England at 'fortress' Twickenham.
"The lads realise what a step up this is and there's a realistic view of where we need to be to win this match," he said.
"The confidence isn't sky-high, it's realistic.
"The last three times we've played England we've lost to them.
"The way we've been playing in recent times, particularly our last three games, we've been good.
"But in physicality, fitness and mental stakes the step up is huge.
"England have spoken a lot about making Twickenham a fortress, but we know that's exactly what it is."
Ireland team: Rob Kearney; Andrew Trimble, Brian O'Driscoll, Gordon D'Arcy, Dave Kearney; Jonathan Sexton, Conor Murray; Cian Healy, Rory Best, Mike Ross, Devin Toner, Paul O'Connell (capt); Peter O'Mahony, Chris Henry, Jamie Heaslip
Replacements: Sean Cronin, Jack McGrath, Martin Moore, Iain Henderson, Jordi Murphy, Isaac Boss, Paddy Jackson, Fergus McFadden
Who will win at Twickenham?