Bolton manager Sam Allardyce admits losing Kevin Nolan and Abdoulaye Faye from his side is a major blow ahead of the Carling Cup tie against Charlton.
Nolan is banned for the next next three matches, while Faye suffered a blow to his head against Blackburn that has ruled him out of Wednesday's trip to The Valley.
Allardyce will be forced to make changes to his starting line-up for the first time in five games against The Addicks and he is hoping some of his squad players step up to fill the void.
"Well Nolan and Faye particularly (will be missed), the core of the team," Allardyce told Sky Sports News. "The reason we are where we are is because the core of the side is so strong.
"Everybody knows the core is down the middle of the team and that's always got to be the thing that's right first and foremost.
"Losing two members of your core is difficult to replace but it will give players an opportunity to come to the frontline and show what they can do and equal the performances or try and better them when they get the opportunities."
Allardyce is especially disappointed to be without the services of Nolan against Manchester United and thinks his captain will feel the same.
"It's a massive setback for us because he's growing as a captain as well as a footballer, so he has an influence on and off the field," he continued.
"It's a blow to us all, and I know how disappointed he will be to miss any game, but certainly the Manchester United game, which he's been so prominent in over the years."
The Trotters remain in third place in The Premiership following Sunday's 1-0 win over Blackburn at Ewood Park.
Sections of the footballing fraternity are already beginning to consider the possibility of Bolton qualifying for the UEFA Champions League this season but Allardyce is not getting overambitious at this stage of the season.
"There's a lot of talk about this Champions League place which for the club at the moment is only a dream that we'd like to try and achieve," he said.
"Nine games gone in The Premiership, I know it's 20 points, a massive total for us, but it's too early to talk about that as a reality.
"As a dream, yes, we've given ourselves a chance and let's try make that dream a reality but our focus is only Wednesday night and after that Manchester United."
Allardyce is keen to negotiate a difficult Carling Cup tie at Charlton before concentrating on Bolton's next Premiership outing against United.
However, with Bolton currently in the middle of a stretch of three games in six days, Allardyce concedes his side face one of their toughest tests so far this term.
He added: "Of course the balance for me is to get a team to beat Charlton, without going into extra time particularly, and then try to give the lads the best chance to try and beat Manchester United to continue this fabulous run we're having in The Premiership.
"Three games in six days makes life very difficult for us, particularly how difficult the game was yesterday and how much effort the players had to put in against an exceptionally good Blackburn Rovers team."