Fleetwood Town boss Uwe Rosler says midfielder Kyle Dempsey suffered concussion during their 2-0 defeat at league leaders Wigan.
Dempsey had a clash of heads with Wigan's Samy Morsy in the first half but the severity of that knock was only clocked by Fleetwood 10 minutes into the second half when the 23-year-old was withdrawn.
Dempsey joins Bobby Grant (knee), Conor McAleny (ankle) and Aiden O'Neill in the treatment room.
O'Neill missed the clash at the DW Stadium due to an unknown but not long term injury with midfielder Markus Schwabl also coming off at half-time after getting a knock on his knee.
Midfielder O'Neill is hoped to be back for Thursday's FA Cup replay at non-league side Hereford on Thursday night but Rosler says Dempsey will have to be assessed.
And Rosler says that without those players Town are struggling to cope against top sides like League One leaders Wigan.
It was Rosler's first return to the DW Stadium since his sacking in November 2014 but the Latics beat his new Town side thanks to two set-piece headers from Nick Powell and Dan Burn.
Rosler said: "We had to take Kyle Dempsey off with concussion, when you are missing then three or four players we cannot cope.
"There is an issue with Kyle Dempsey, it is not getting easier that is for sure but we are O.K.
He added on Dempsey's injury: "I'm not a medical expert, I got told that with concussion there are several different levels and I got told that does not necessarily mean that he will miss Thursday's game but there is obviously a chance.
"I got told just after the second half started that Kyle is not right and we acted immediately."
Losing Dempsey was a blow but paved the way for development squad midfielder Harrison Biggins to make his Football League debut.
It was a baptism of fire for the 22-year-old youngster who joined the club from non-league side Stocksbridge Park Steels in the summer.
And Rosler was pleased with how he handled the situation and coped with playing against Wigan's experienced midfielders Samy Morsy, Max Power and Lee Evans.
He said: "He did alright, coming on in a game like that, 2-0 down against Wigan with Evans and Power and Morsy in midfield and you make your debut.
"The boy did well.
"I always like him, I think he has something that will be very useful for us in the years to come, I felt a little bit sorry to throw him in in a game like that but I'm happy in general how he dealt with that situation."
Wigan opened the scoring through Powell who pounced on Lee Evans' short corner in the seventh minute.
Town should have levelled as Ash Eastham's header hit the bar and Jack Sowerby wasted a golden opportunity as he and Devante Cole took on Dan Burn.
Sowerby should have slid the unmarked Cole in on the right but he honed in on goal and Wigan recovered.
It was all Town but Wigan put the game to bed in the 37th minute from another set-piece as Evans again found Burn who nodded home.
And Rosler says the defending on that second goal was his only disappointment of the day as he highlighted the good performance of central midfielder George Glendon.
He said: "The game had not even started and we were 1-0 down after that we cut them wide open.
"We were the better team but that last little bit of quality, the last pass and the last shot or cross and a little bit of bad luck with the header on the bar did not allow us to get a very deserved equaliser.
"What only disappoints me is the second goal.
"It is a free header and they had another chance from a free header.
"I think in both boxes we could have been better.
"They have in both boxes more quality than we have and that cost us in terms of ability to fight and try and come back into the game.
"I can't criticize any of my players because they gave me a lot against the best team in the division but that last little bit of quality we did not have.
"Today we played some decent stuff, especially in the first half but the goals decide games and I think for our young team I was fearing when the second goal goes in, with their quality I was fearing we could go under but we did not and that is obviously positive for us.
there were some very good performances George Glendon was very good."