Craig Casey's shoulder injury appears to be less serious than initially thought and the Ireland scrum-half has not yet been ruled out of Munster's Champions Cup tie with Castres on Saturday.
The 26-year-old was taken off with eight minutes to play of their 27-25 loss to Toulon on Sunday with head coach Clayton McMillan commenting afterwards that it "looks reasonably serious".
That had put his participation in the early rounds of the Guinness Six Nations, which starts on 5 February against France, in doubt but there was a more upbeat assessment from the province at Tuesday afternoon's media briefing
"It's a big boost that he hasn't been totally ruled out but he still has a significant bang on his shoulder so that's day by day," defence coach Denis Leamy told RTÉ Sport.
"Fingers crossed that Craig can make it and if there's anyone that can work hard in the meantime to get there, Craig certainly will, so fingers crossed."
Fellow scrum-half Paddy Patterson has been ruled of their Pool 2 round-four meeting against the French side with a head injury but Leamy says the squad are confident that Ethan Coughlan and academy player Jake O'Riordan can slot in.
Lock Jean Kleyn, who the club today announced will join Gloucester next season, missed the loss to Toulon with a calf injury but is fit and available for Saturday.
Prop Oli Jager has recovered from a head injury, while Diarmuid Barron (knee) is being assessed with his availability to be determined later in the week.
Wing Calvin Nash (shoulder/head) has been ruled out.
Forward Tom Ahern missed the game with a neck injury and will be assessed as the week progresses to determine his availability.
Munster conceded 14 penalties in the narrow loss to the French side with 14 points conceded during captain Tadhg Beirne's time in the sin-bin either side of half-time.
The Ireland forward was also shown a yellow card at the start of their round one loss at Bath for an infringement which led directly to a penalty try, while the English champions scored twice more before the British and Irish Lions player returned.
Centre Alex Nankivell also spent ten minutes in the bin for inexplicably playing the arm of Toulon scrum-half Ben White at a ruck.
"I think both players understand very clearly, black and white, that it's not good enough and those sort of actions are not what we want so it's not a hard conversation, to be honest," said former Ireland flanker Leamy.
Munster had recovered from 21-13 down in the second half to lead by a point with four minutes left.
English referee Karl Dickson penalised centre Tom Farrell for "taking the space" around the tackle area, in a call most observers felt very harsh.
"Look, Karl Dickson is a world-class referee, he saw it as a penalty, we just have to move on," said Leamy.
Munster, thanks to a late defensive play that secured a losing bonus point, sit on six points in Pool 2 and will secure qualification for the round of 16 if they beat Castres in Limerick on Saturday (5.30pm).
A bonus-point win could, depending on results elsewhere, get them into the top two and earn a home knockout tie.
Two seasons ago, Munster lost a home European game to Northampton, and drew with Bayonne.
So far in the URC this season, both Stormers and Leinster have won in the Limerick venue.
Leamy stressed that Munster need to make their home ground more unappealing to visitors.
The two-time Heineken Cup winner said: "A lot of teams have come in the last 18 months and there's been, I wouldn't say a welcoming committee out for them but it certainly hasn't been the Thomond Park of old.
"You'd love to have a hostile atmosphere waiting for teams that are travelling but we have to create that as a team. That comes from us first and then the fans buy in.
"It starts with us, finishes with us. Simple.
"We [the coaches] won't have to touch on the Thomond Park factor at all.
"We've got a short week, we've got to get our lineouts right, we've got to get our 'D' right, our attack right, our scrum right, we've got to get our exits right.
"Thomond Park will look after itself."
Follow a live blog of Munster v Castres (Saturday 5.30pm) on rte.ie/sport. Listen to live radio commentary on Saturday Sport on RTÉ Radio 1.
