Traditionally the biggest Gabba crowd of the Lions' season, the clash against Collingwood is also the only time fans in Brisbane will be treated to a nationally televised Friday night match on their home ground.
Johnstone said it was a great opportunity for the Lions to shine and show their 2-1 season start was no fluke.
“It's going to be huge,” he said.
“It's always good to get Friday night games because the football world will be watching. You want to show what type of team you are and what you stand for.
“They (Collingwood) play in front of big crowds every week so it's like water off a duck's back to them but if we want to play in finals and be competitive we can't let crowds get to us.
“We've just got to enjoy the atmosphere and enjoy playing a quality team, that's why you play footy.”
Johnstone played 160 games for Melbourne over 10 seasons before heading north in 2008, and lined up in a number of Queen's Birthday matches against the Pies in front of huge crowds.
He said the key to success on Friday night was replicating the performance against the Sydney Swans last weekend.
Coach Michael Voss made it extremely clear what he expected of the Lions, Johnstone said.
“Vossy laid down the law during the week and to the boys’ credit we all stood up and got the result we wanted,” he said.
“It's been a short week so the focus has been on recovery and we'll approach it the same way we did against Sydney.
“If we perform in the areas that Vossy wants us to we can stamp some authority on the competition.”
Johnstone has been dominant in the first three games of the season, starring with 37 disposals against the West Coast Eagles in round one and showing his class in the Lions' win against the Swans with a number of pin point passes to Jonathan Brown and Daniel Bradshaw.
Whereas the Swans played a lot of one-on-one match-ups right through the four quarters last week, Johnstone believes Collingwood will pose a different challenge.
“They have a lot of rotations with quality players through the middle so it's going to need a big effort as a team because there'll be a lot of players on different players all the time,” he said.
“We'll pay close attention to some players and if they slip away we'll have to look to our teammates and swap over. It's going to be a very fast game.”
