Alex Cuthbert - England's two-try nemesis when Wales crushed their Grand Slam hopes four years ago - is on red alert to start Saturday's RBS 6 Nations showdown in Cardiff.
Wales are giving wing George North, a scorer of 28 tries in 66 Tests, the maximum possible time to recover from a leg injury.
He was involved in the Wales captain's run session on Friday, but we understand that his fitness fight could ultimately be a losing one.
Cuthbert, who has won 44 caps but not started a Six Nations game since Wales lost to England at Twickenham last season, also took part in the Principality Stadium run-out, as did uncapped Scarlets speedster Steff Evans.
Cuthbert claimed two second-half touchdowns during the 2013 clash in Cardiff, when Wales' record 30-3 victory not only denied England a tournament clean sweep, it meant the home team were crowned Six Nations champions on points difference.
Fly-half Dan Biggar, though, is thought to be less of a fitness concern after going off at half-time against Italy in Rome following a blow to the ribs. Biggar and North were both named on Thursday in Wales' starting XV.
Asked about North's chances, Wales assistant coach Robin McBryde said: "I can't go into 50/50s or 60/40s, or whatever. All I can do is rely on what the medics are telling me.
"They (Biggar and North) have done everything asked of them up until now, and it's obviously a close call because we are leaving it late. We are just making sure that whatever happens, we are ready for kick-off tomorrow."
Wales do not need to release their confirmed starting line-up until Saturday afternoon, and McBryde added: "Rob (Wales' interim head coach Rob Howley) will make the final call on that. You have to speak to Rob. What will be, will be.
"Obviously, we have got contingency plans in place. We've got Steff Evans and Alex Cuthbert with the squad as well.
"Everybody has got their heads on psychologically. Everyone is making sure they are preparing the best they can, ticking off everything they need to cover."
England are chasing a fourth successive Six Nations victory over Wales and they arrived in Cardiff on Friday as favourites, seeking a 16th win on the bounce against all opponents.
The week has not been immune from the mind games that accompany one of Test rugby's fiercest rivalries, but McBryde played down England's request for the Principality Stadium roof to remain open.
Both teams have to agree in order for it to be closed, otherwise it stays open.
And McBryde sparked laughter during his press conference when a phone rang just in front of him, promptly picking it up and answering: "Eddie? Sorry mate, I am in the middle of a press conference.
"He just rung me now to say he has changed his mind (about the roof), apparently! It is going to be a fantastic occasion.
"It is going to be dry tomorrow, so it (closed roof) won't have that much of an effect on the game.
"He has probably consulted one or two before making the decision, but from our end it doesn't change a lot, really."
And asked about the traditional Wales versus England intensity, former Wales forward McBryde said: "We are neighbours, aren't we? I have got two English brothers-in-law.
"It is that English-Welsh rivalry, and wanting to get the better of your neighbour. It's as simple as that."
Wales currently show just two changes from the side that beat Italy 33-7, with props Rob Evans and Tomas Francis both handed starts after impressing off the bench at Stadio Olimpico.
"I thought we scrummaged very well last week," McBryde added.
"Our dominance grew as the game wore on. We've worked hard on our reputation as a scrummaging unit, and we will rely on that.
"That's the challenge for the two (props) that are starting on Saturday, that they start off in the same vein and don't hold anything back because we know we've got two good scrummagers on the bench as well.
"Across the board, they (Wales forwards) all offer something with ball in hand as well.
"I know there is lot of talk with regards to the ball-carrying abilities of the English pack, but I think the Welsh pack have got equally a number of effective ball-carriers amidst them as well."