"I've not even thought about that," McAllister said. "We've got to look at positive things, look at winning, and look to go through."
The non- performance by his team at Elland Road on Monday has certainly perplexed McAllister.
"We've got to improve right throughout the team, from one to 11," he added. "We have to hold our hands up and admit that we didn't play well.
"But you'll see a different Leeds side tonight. I'm absolutely sure that the quality, the composure and the way we approach the game will be different.
"Pressure does tell on occasions. Your decision-making can be out, also your touch and your choice of pass.
"It's a performance that surprised me, I've got to admit, but we've got that one out the way and go into the game tonight knowing what's at stake. And we're going to fight.
"The fortunate thing is that it's half-time (in the play-off) and we've got more than 45 minutes," McAllister said.
"We've got 90 minutes to get the goal back and to win the game. It's not a case of being gung-ho, because there's plenty of time. It's a case of playing with our heads.
"The first goal's going to be very important and it won't be a problem for me if we go and score early, but we don't need to flood men forward.
"We've got to recognise situations and, when it's on, we'll commit men. We're brave enough to do that."
If extra-time and penalties are required, the team will not be caught short of preparation either. On the subject of whether Leeds have concerned themselves with set-pieces from 12 yards, McAllister said: "Yes we have. They're looking not bad.
"But we're confident in the fact that we've gone on our travels recently having to win games under pressure in order to get us into the play-offs. Nothing changes, we go into this game and we've got to win.
"It has to be enjoyable. Life brings you loads of different pressures and this is good pressure, this is the pressure you want to be involved with and this is the sort of game you want to be involved in.
"Carlisle were better (at Elland Road) and they've edged themselves in front, but they can be sure it's going to be a tough battle.
"We're going to fight, scrap and go right to the final minute.
"Many people saw us as favourites at Elland Road, Carlisle having a goal start will now be deemed favourites. So we go into the game as underdogs.
"They've got the expectation and the pressure of the home fans which we had the other night so the roles are reversed. We'll see how Carlisle cope."