INJURY doubt Jonathan Sexton must train at least twice this week to be considered to face New Zealand on Sunday, according to Ireland boss Joe Schmidt.
Sexton limped out of Ireland's lacklustre 32-15 defeat to Australia at half-time with a hamstring problem.
Head coach Schmidt will receive an update on Sexton's condition today, once Ireland's medics have examined scans.
If the prognosis is unclear, Schmidt admitted Ireland can ill afford to gamble on the 28-year-old Racing Metro playmaker's availability.
Schmidt explained: "I guess on Monday we'll find out the degree of his injury and then that will either make a decision easy for us, because it looks good or it doesn't look good.
Steve Hansen's side may have to do without 100-cap fly-half Dan Carter though, who suffered a leg injury of his own in London.
New Zealand's 24-year-old fly-half understudy Aaron Cruden already boasts 27 caps, in contrast to Ireland's out-half back-ups Paddy Jackson and Ian Madigan who have a combined cap total of 11.
Schmidt admitted that experience gap will require careful handling should Sexton miss out.
Gordon D'Arcy could very well be primed for a midfield recall if former Leinster pivot Sexton is laid low, to offset any potential inexperience at fly-half.
Schmidt added: "One of the things is the number of Tests they've played. Aaron Cruden's accumulated almost 30 Tests (whereas) Paddy Jackson and Ian Madigan have a handful each.
"That's a very big gap in terms of learning, experience and opportunity to maybe make some errors and learn from them.
"So it's important for us to try to get the right players around the 10 if it's not Johnny."
Schmidt called upon Ireland supporters to stick with his squad, who he described as a "work in progress", and predicted a hectic week trying to solve a host of shortcomings in his side's approach.
He added: "This All Blacks team put 47 points on this Australia team in Australia, when the Wallabies first got together under Ewen McKenzie.
"I think that's going to make it very tough for us.
"At the same time I would implore the public to hang on in there.
"We've got a lot to do: our set-piece, our defensive line, our kicking game, there's a lot to work on and unfortunately there's no magic fix.
"I would love it if there was a panacea to fix all ills there but it's going to be gradual."