Nigel Worthington admits Northern Ireland are down to the 'very bare bones' for the Euro 2012 qualifier against Estonia on Tuesday.
Northern Ireland's hopes of qualifying for the finals suffered a dent on Friday night following a 1-0 home defeat at the hands of Serbia.
Kyle Lafferty and Paddy McCourt missed the game due to injuries and will not travel to Estonia, while Jonny and Corry Evans are suspended after being booked for the second time in the qualifying campaign.
Sammy Clingan is a fitness concern after sitting out the Serbia game due to illness and Worthington is waiting to see who will be available to face Estonia.
"We're down to the very bare bones," admitted Worthington.
"Lafferty and McCourt won't make it and we've lost Jonny and Corry to second yellows.
"We'll have to see where we are with Sammy and we'll go back and assess everything in the cold light of day.
"Sammy was sick through the night and he was very weak so he never had a chance of playing.
"We'll see him in the morning and if needs be the doctor will see him again. Hopefully it's a 24-hour virus and he's back in the group tomorrow."
With Derby forward Jamie Ward an earlier withdrawal from the original 23-man squad, Worthington is considering bolstering his party with members of the Under 21 squad.
'Keep our heads up'
Meanwhile, Steven Davis is eager to get back on to the pitch after his error allowed Marko Pantelic to score Serbia's winner.
"I think the best thing is that we've got another game coming up and if you have a bad day at the office then you have to get back into it," said the Rangers midfielder.
"It's obvious that we felt the loss of Kyle and Paddy (against Serbia) and we'll also now miss Jonny and Corry through suspension.
"But Nigel has told us to keep our heads up, move on from this and hopefully still be in with a shout."
Lee Camp, who made a series of important saves and walked away with the man-of-the-match award, also expects a big reaction from Northern Ireland.
"There's still hope at the end of the tunnel, so we'll be looking to put things right," he said.
"We will be okay, there are big characters in the dressing room and we've all been here before. It's not over yet and there's still everything to play for."