Chiedozie Ogbene and Alan Browne have emerged as doubts ahead of Ireland's upcoming Euro 2024 qualifying double header.
The Republic of Ireland will travel to face Greece in Athens on 16 June, followed by a home clash against Gibraltar three days later.
Stephen Kenny’s squad have been training in Bristol this week and the manager issued the injury update, also confirming that Everton prospect Tom Cannon missed the camp due to a bout of tonsillitis, while club team-mate Seamus Coleman will miss the games due to a knee injury.
"Chiedozie Ogbene had a hamstring tear with Rotherham and hasn’t been able to participate this week, so we’ll have to see how that is," said Kenny. "Alan Browne as well, coming back from a medial injury.
"These are dilemmas for us. Tom Cannon hasn’t been here this week due to tonsillitis."
Speaking about this week’s training camp, which was primarily aimed at the Championship-based contingent in the squad, Kenny said that it has proved very useful.
"We found Bristol very valuable. Bristol City have a terrific facility, we had it to ourselves. We thank them for that," said Kenny, having previously admitted that his squad were caught out to a certain extent for last summer’s window, which contributed to the disappointing away defeat against Armenia.
"It’s been an important week because we can set individual programmes and they can do whatever runs that we set them and can monitor with the technology, but nothing beats playing football, and setting the drills, and the players can really benefit from that.
"The Championship is the only league that finishes six weeks before the international window in June.
"The Greek players will all be playing right up until [the qualifier]. Spanish, Italian and the Premier League are the same, but because the majority of our players are in the Championship it is a challenge we have to take on. So these four days were important.
"The other side of it is they play 46 games in the Championship. In a World Cup year, it has been even more condensed with midweek matches every week, with lads playing on injured, so there is a fine balancing act where we had individual programmes tailored for each player."
Kenny invited a number of fringe players to the Bristol gathering and said that they all impressed during the week, giving him options for the rest of the campaign.
The final squad for the upcoming qualifiers will be confirmed next week ahead of the pre-Greece camp in Turkey, which will include a friendly match in Antalya.
And Kenny believes the nine-day Turkey trip should prove invaluable for the squad ahead of a tricky test against an improving Greece side, as Ireland look to put some points on the board following the narrow defeat to France in the group opener in March.
"[In Turkey] it will be important to replicate the conditions we will find in Greece," said Kenny. "They are a good team that won their Nations League group so we will have to perform at a high level.
"We need to make sure that we’re absolutely 100%. Going to Turkey will help us by training in similar conditions, getting ourselves ready by training for nine days there.
"We go to Athens on the Wednesday and play against Greece on the Friday before we come back and play.
"At the moment, we’re firmly focused on our preparations for that. I think that our preparation here and in Turkey will give us a chance. Hopefully some of the players can come through their injury difficulties and if so, we want to make sure we’re ready."
Ireland's Bristol training-camp squad: Max O'Leary (Bristol City), Ed McGinty (Oxford United), Brian Maher (Derry City); Danny McNamara (Millwall), Callum O’Dowda (Cardiff City), James McClean (Wigan Athletic), Dara O’Shea (West Bromwich Albion), Seán McLoughlin (Hull City); Jayson Molumby (West Bromwich Albion), Josh Cullen (Burnley), Will Smallbone (Southampton), Mark Sykes (Bristol City), Neil Farrugia (Shamrock Rovers), Jason Knight (Derby County), Jack Taylor (Peterborough United); Chiedozie Ogbene (Rotherham United), Troy Parrott (Tottenham Hotspur), Michael Obafemi (Burnley), Adam Idah (Norwich City), Will Keane (Wigan Athletic).