Birmingham boss Alex McLeish admits concern over his players suffering burn-out is one of his biggest fears in the battle to ensure survival.
Blues have slipped into the bottom three after a woeful performance in Saturday's 3-1 home reversal against fellow strugglers West Brom.
McLeish was deprived of several key players through injury, including midfield duo Barry Ferguson and Craig Gardner who will again be absent for Wednesday's meeting with Everton at Goodison Park.
The former Scotland boss has never doubted the commitment and honest endeavour of his players.
But he is worried about the danger of players running out of steam given their pursuit of cup glory on two fronts alongside the fight to retain top flight status.
McLeish, whose side entertain Bolton in the FA Cup quarter-finals on Saturday, said: "You definitely worry about burn-out because of the amount of games they've played.
"The concentration that was there for the Stoke game and then the Arsenal game at Wembley in the Carling Cup was missing at the weekend.
"Whether that was tiredness or burn-out, then that's the only excuse I would be prepared to make for them.
"There's not a lot you can do about it.
"I hear some managers saying that they never got anything out of certain players who had played in the World Cup until December time.
"We know that's the kind of things burn-out can do to you.
"But we're not feeling sorry for ourselves. We've got to get on with it."
McLeish acknowledges Blues face a difficult run which includes away games with Chelsea, Liverpool and Tottenham.
But he has seen his side rise to similar challenges earlier this season and will expect the same again.
He said: "There was a period earlier in the season when people looked at the fixtures and tipped us to get no points out of 12.
"We ended up with six or seven points through beating Chelsea and drawing with Manchester City and Tottenham during that run.
"We know it's a hard run-in but we're capable of taking points.
"If I can get all my players back from injury, we've got a good chance (of staying up).
"If we get further injuries, then you are down to the bare bones and maybe you are bringing in young players who have never played in the Premier League before."
McLeish is refusing to be drawn on all the speculation regarding the club's finances and whether or not bonuses will be paid for the Carling Cup success.
He said: "It is not my department. It is not something I want to start debating in public.
"I am not sure if the bonuses have been paid but I'm sure you would have heard by now if they hadn't been paid!
"I don't get involved in the financial side. I leave that up to the board and as far as I'm aware, everything is fine.
"That was the last statement I heard at the weekend."
Birmingham defender Martin Jiranek is set to return after missing the West Brom encounter with a thigh injury.
Ferguson (broken rib) and Gardner (calf) are still sidelined and McLeish will run a late fitness check over striker Nikola Zigic who missed the Baggies game with a groin problem.
Defender Liam Ridgewell is expected to play despite needing an injection to ease a groin injury minutes before the kick-off against West Brom.
