Ireland duo Tadhg Furlong and Iain Henderson in fitness race
Tadhg Furlong and Iain Henderson face a race against time to prove their fitness for Ireland's Six Nations clash with Wales on Saturday.
Lock James Ryan has been passed fit after a groin issue, so will be free to contest selection for the weekend's Dublin battle with Wales.
But tighthead prop Furlong and second row Henderson are yet to prove their fitness after hamstring complaints.
Defence coach Andy Farrell admitted Ireland boss Joe Schmidt could even wait until Thursday morning before finalising his line-up, as Furlong and Henderson fight for fitness.
"Tadhg is hitting his markers and he's training well," said Ireland assistant coach Farrell, of Furlong.
"He's not been in full training, he's been doing a bit-part of stuff and we'll make a decision on that Wednesday night, Thursday.
"James Ryan has been training with us fully for the last few days, so he's fully fit.
"Ian Henderson, a bit like Tadhg, is hitting his markers and pushing in the right direction. We'll assess how he pulls up after two hard days of training.
"There's not a risk, we wouldn't take risks. We back the squad that we've got, the full squad we've got, we've got quality players across the board.
"We'll make the right decisions come Wednesday or Thursday."
Ireland's meticulous boss Schmidt would normally demand his players prove their fitness on the Tuesday of a Test week building to a Saturday match.
The former Leinster boss has bent on that strategy in the past however, and so may well hand British and Irish Lions duo Furlong and Henderson further time to prove their readiness for battle.
Leinster prop Furlong has quickly emerged as the cornerstone of Ireland's scrummage in his 21 caps across just three years of international rugby.
The 25-year-old excelled on the summer's Lions tour, starting all three Tests against New Zealand.
Ulster lock Henderson can count himself hugely unlucky not to have featured in any of the Lions Tests against the All Blacks, leaving Ireland sweating on the fitness of two key performers ahead of the Wales clash.
Leinster's fast-improving tighthead Andrew Porter could step in to start if Furlong fails to make the fitness grade, with Devin Toner and James Ryan a likely lock combination should Henderson miss out.
Garry Ringrose has shaken off ankle trouble, though Ireland may consider the Leinster centre not ready for Test action given he is yet to taste any match action after his return to fitness.
Munster's Chris Farrell could partner Bundee Aki should Ringrose not be deemed match-ready, with Robbie Henshaw sidelined for up to four months after dislocating his shoulder in the 56-19 win over Italy on February 10.
"Garry has come back into camp today, he's looking great," said Farrell, of Ringrose.
"I actually said to him 'have you put a bit of weight on?' He's looking in great nick.
"It's good to have him back, he cut us open a few times in training like he normally does.
"He's short of game time, obviously, but he's a class player and he slotted straight back in today."