Martin O'Neill joked he disliked the Euro 2016 draw but vowed to leave no stone unturned after the Republic Ireland were handed a tough task.
They will play Sweden, Belgium, who are top of FIFA's world rankings, and Italy in Group E in France next year following Saturday's draw.
Ireland qualified by beating Bosnia in the play-offs in November and boss O'Neill admitted they could have been given an easier passage.
"I thought I was going to enjoy the draw, I'm not sure I have done. Now we can take time out to study opposition players so that by the time of the games we know everything about them. There is no reason why we shouldn't," he said, speaking to the BBC.
"It couldn't get tougher. Italy should be in Pot One, they have not dropped down the rankings that much. It's difficult, (they are) games to look forward to for the fans but it couldn't be tougher for us.
"Sweden is a game to look forward to, so let's go for it. Sweden are not a one man team, they were quite strong in qualifying but (Zlatan) Ibrahimovic is a top class player.
"About 90 minutes ago I would have said we were delighted to be here, now I'm not so sure! Our support will be fantastic, and this is great for them."
Ireland start against Sweden on June 13 at the Stade de France before heading to Bordeaux to play Belgium on June 18 and finish against Italy in Lille on June 22.
Goalkeeper Shay Given tweeted: "Tough draw for us @FAIreland but still very excited about next summer, bring it on."
But former Republic of Ireland defender Mark Lawrenson told the BBC the squad's underdog tag in the group could help them as they have no superstars.
He said: "We are better as underdogs. As soon as they are favourites we collapse. We could be underdogs in all three games. The great thing is we have no star players.
"Probably it's the least talented squad who have ever qualified so that speaks volumes for the manager and Roy Keane and the coaching staff. Because they have no stars they are very difficult to beat. They will have a real go. The last time in the Euros we bombed but I don't see that happening this time.
"It's a long way off until we play, players will get injured and have losses of form. You never know."