Glenn Whelan has become the Republic of Ireland's latest injury concern for the must-win Euro 2020 qualifier against Denmark on 18 November.
The Hearts midfield was forced off with a hamstring problem in the first half of Sunday's League Cup semi-final defeat by Rangers.
Whelan, 35, has played in five of the Republic's seven Euro 2020 qualifiers.
Republic skipper Seamus Coleman is suspended for the game while keeper Darren Randolph is an injury doubt.
Matt Doherty came off in Wolves' draw with Arsenal on Saturday after suffering a recurrence of a knee injury but is expected to be in contention for his club's Europa League game against Slovan Bratislava at Molineux on Thursday.
John Egan was forced off by illness in Sheffield United's weekend win over Burnley but Blades manager Chris Wilder played down the issue after the game.
"He's OK. I've just had a little peek to see how he is. He just didn't feel too well," Wilder told the Sheffield Star.