Martin O'Neill believed luck was not with his Republic of Ireland side at Saturday's Euro 2016 draw in Paris.
"It could not have been tougher for us," said the Irish manager after being grouped with Belgium, Italy and Sweden.
"I think Italy should have really been in pot one, then we have the top-ranked team and Sweden to boot.
"I thought I was going to enjoy the draw, but now I am not sure I have done. But I will get my head around it and focus on the job after Christmas."
O'Neill, whose team qualified by beating Bosnia-Herzegovina in the play-offs, added: "Sweden is a game to look forward to, so let's go for it.
"They are not a one-man team, although Ibrahimovic has been a top class player.
"I watched Sweden in the play-off games and they were quite strong.
"We will take time out to study opposition players so that by the time of the games we know everything about them."
Republic of Ireland fixtures (all times BST)
Monday, 13 June
Republic of Ireland v Sweden (17:00)
Saturday, 18 June
Belgium v Republic of Ireland (14:00)
Wednesday, 22 June
Italy v Republic of Ireland (20:00)