Ireland have made great strides since Trapattoni's appointment as manager three years ago, going unbeaten in their qualifying campaign for the 2010 World Cup before being defeated in controversial circumstances by France in a play-off.

They currently sit joint top of their group on the road to next summer's European Championships and have won six of their seven games in 2011.

The Republic go into tomorrow night's friendly against Croatia at the Aviva Stadium off the back of four straight victories in which they scored 10 goals and conceded none, and Bilic is impressed with his opposite number's work.

"I watched Ireland's last few games to prepare for this match and they were good in every one of them," Bilic said.

"They won most of them and they really impressed me. I am looking forward to tomorrow night's game because it will be like a real qualification game.

"In history Irish teams have always been good, passionate, solid, aggressive teams but Trapattoni has turned them into an extremely well-organised side.

"That is why the last few results have not surprised me. He is really doing a great job."

Bilic appears to have left no stone unturned in getting a feel for the Irish in the build-up to tomorrow's game, revealing today he took his squad to see Celtic rock band the Pogues in concert in Croatia a few weeks ago.

"We have done the homework - we even went to see the Pogues in Zagreb!" Bilic said.

"They were playing in a small open-air arena to about three or four thousand people. They are very popular - they are a world-class band."

With several Barclays Premier League players among their ranks, Croatia have plenty of star quality themselves, not least in the shape of Tottenham midfielder Luka Modric, who has been the subject of constant transfer speculation this summer.

It is something Bilic has discussed with the player and he is confident Modric is in the right place mentally to focus on the job in hand tomorrow night.

"Of course I have spoken to Luka," Bilic said.

"He is good in his head, but you have to ask Luka about this thing. It is between us of course, but I am sure that tomorrow night he will be concentrating on his football."

Another player who has been heavily linked with a move away from Spurs is Ireland captain Robbie Keane and the 31-year-old made it clear earlier today he expects to leave before the transfer window closes.

Having fallen down the pecking order at White Hart Lane, Keane was on loan at Bilic's former club West Ham for the second half of last season as the team were relegated to the npower Championship.

The striker has indicated he wants to remain in the top flight, but Bilic feels it might have served Keane well to keep playing at Upton Park.

"He is still a great player and he is not old - in fact, he is maybe in his best stage," Bilic said.

"He only needs to play more regularly for a club. It is a shame he didn't stay with the Hammers."

On West Ham's plight, Bilic - who spent a season and a half as a player at the club in the 1990s - added: "It was sad - it's my team and I played the best days of my football life there.

"It is a big shame for the Premier League because it is a good club and I think that every Premier League fan is disappointed that they are down. I hope they will come back."