The reigning Magners League Champions head to Dublin on the back of an indifferent season but McGahan insists that knockout rugby is all about what happens on the day rather than what has gone before.
And while what has gone before hasn't always been perfect so far this term, with regular season loses to this weekend's opponents both home and away and a 50 per-cent winning return in 18 league games, McGahan knows his squad have what it takes to turn things around and reach the inaugural Magners League Grand Final.
"It's a one-off game this weekend," said McGahan, who welcomes back Doug Howlett, Keith Earls, John Hayes and Mick O'Driscoll to his starting line up for the trip to Dublin.
"I know it's a well-worn cliché but it's going to be 80 minutes and whatever form you're bringing in, whether it's high, low or indifferent, it's where you're at mentally that's going to determine the result.
"We haven't shied away from the fact that we've been inconsistent this season. We've had some excellent days out but, at the same time, we've let ourselves down with inconsistency right across the park. It hasn't been limited to one or two areas; it's been setpiece, it's been attack, it's been defence, it's been breakdown, goal kicking and field kicking.
"We recognise that when we get all those things right we can play the game that we're trying to play, whether that's a really tough, forward orientated, grind-out game with kicking or whether we're trying to play with a bit of width. That's what every side's aiming for and we haven't been able to do that consistently enough this season.
"But even though we didn't win at the weekend, we felt that we'd done enough to get a result and that's given the squad a big boost.
"We're heading into a semi-final, away from home, in Dublin, against Leinster, so there's plenty to be pleased about and we're really looking forward to that aspect of it."
The last time Munster travelled to the capital things didn't go their way. A humiliating 30-0 drubbing wasn't what the Red Army were expecting even if they were hit hard by injury and a disruptive start to the season.
The two sides met again last month, this time at Fortress Thomond Park, but, again, things didn't go quite to plan, even if the scoreline was far closer.
Munster were beaten 16-15 as Leinster enhanced their own chances of a home semi-final and left McGahan and his men with a massive battle just to make the top four.
But while those loses weren't what McGahan wanted to see, he does admit that lessons can be learned ahead of the one derby clash that really, really matters.
"It was well documented where we were at that particular stage at Round 5 of the competition," added McGahan, in reference to the disappointing showing at the RDS in early October.
"We'd had a very disrupted period and were well beaten on that night but we had absolutely no excuses to go down 16-15 at home last time out.
"The biggest lessons that we needed to get out of that were (1) our kicking game in terms of when we were kicking and how we were kicking, and (2) the need to stop Leinster's kicking game.
"They really pinged us in our own half at the back end of the last 20 minutes and we put a lot of ball down on the catch side of things and that put us under an immense amount of pressure.
"I think the kicking game is going to be a huge part of the weekend."
Guinness PRO12
Suite 208, Alexandra House,
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Ballsbridge, Dublin 4, Ireland