"In a way this is like knock-out football. They will scratch that game and we have to scratch that game as well and start all over again," said Heaslip.
"It is like the back-to-back games in the Heineken Cup come Christmas time. They are always tough and you know a little bit more about each other and the second game is always a whole lot tighter than the first one, although I don't know how much tighter it can get.
"It is going to make for an interesting second game this week. We'll see what we did well, what we didn't do well., what we've got to work on and what we want more of. I think our patterns worked very well in Brisbane when we got into the way we wanted to play the game.
"We caused a lot of problems. We made little line breaks and half line breaks, but we need to hold onto the ball a bit more and play in the right spots this weekend..
"We made a couple of silly errors and lost some momentum and gave it to them. Those are the things we have to work on and I'm sure they have a lot of stuff to work on as well - we know they are going to be coming at us hard next week."
Heaslip, along with Mike Phillips, Adam Jones, Tom Croft and Alun Wyn Jones, will be targeting a third successive Test win with the Lions in Melbourne this weekend. The last group of players to do that were way back in the first three tests in 1974.
This weekend's game will also be about winning a series for the first time in 16 years and the significance of the occasion is certainly not lost on the Irish back row man.
"In South Africa the win in the third Test was about restoring a bit of pride into the jersey. That's kind of what that tour was all about, especially with the way we lost that second Test," said Heaslip.
"We knew the jersey wasn't going to be worn again for four years, and that is a long time for a jersey not to be worn. We wanted to do it right and on that last day we did.
"We knew the importance of starting off well here and just how physical the game was going to be. We got a bit of luck in Brisbane and we came up with the win, which we are delighted about, and it has helped to build momentum and confidence.
"They played quick in the first Test and they were really accurate on their own ball at the break down. They keep coming at you in waves and are always looking for miss matches with backs and forwards.
"They have a good kicking game and they are just a very good team and we know the challenge that is going to be coming at us next weekend. They've had a run out now because they hadn't played in a couple of weeks so that's out of their system and there will be no excuses for them."