The Republic are just a point behind second-placed Sweden in World Cup qualifying Group C and, with Germany hot favourites to win the group, Friday night's clash is of huge importance.
And Hamren says his team know they will need to perform very well if they are to secure a vital three points.
"I think Ireland are a really good team," he said on Thursday. "I am full of respect for them.
"They played in the Euros last summer and, if you see the away statistics from Ireland, you can see they are a really tough team to beat.
"I expect a tough game tomorrow and they always, in my opinion, play with their heart for the green shirt.
"The players are ready and I am ready. It will be a tough game and we need to be really good. We have set our goal to be that good.
"We will see what happens, they are only one point behind us. It is a really important game for us both."
Ireland boss Giovanni Trapattoni says he would prefer the retractable roof at the Friends Arena to be left open but, with extremely cold weather forecast, the Swedish Football Association are likely to have other ideas.
Hamren said: "I don't think it is a big problem for the players because they are running but, for the supporters and for me and Trapattoni, it is better to have it closed, then we don't have to have long stockings on.
"In my opinion let it be closed, it is going to be cold tomorrow. For those who are going to be paying a lot of money to see the game, let them have it."
Sweden have a superstar in their ranks in the shape of forward Zlatan Ibrahimovic and Ireland captain Robbie Keane this week joked that his team-mates may need to "try to kick" the Paris St Germain man "as far as we can".
Ibrahimovic said: "I am prepared for everything. If the opponent has to do everything to stop the other team, that is what we have to do also.
"Let's see how the game will be. Hopefully it will be a nice game and lots of people enjoy it."