Marco Tardelli has admitted he is "scared" by what Zlatan Ibrahimovic could do to the Republic of Ireland's World Cup dreams.

Sweden’s enigmatic striker will line out at the Aviva Stadium on Friday evening for a game which could go a long way towards determining which, if either, of the sides has a chance of making it to the finals in Brazil next summer.

Giovanni Trapattoni's side drew 0-0 in Stockholm in March on a night when the Paris St Germain star largely failed to live up to his billing.

However, Tardelli, Trapattoni's assistant, knows only too well what Ibrahimovic can do and fears the consequences of failing to contain him.

Asked if a series of injury problems for the Swedes would benefit Ireland, he said: "I hope so - but the best player is on the pitch and I am very scared about him because he is a very good player.

"He is the first player in Sweden. Ibrahimovic, for us, I would prefer to stay out.

"Ibrahimovic is a player who, if he decides to play, he plays very well and scores goals.

"Sometimes it can happen that he doesn't play very well, but I would prefer to have him in my team, very much. He is in the top 10 players in the world, he can do everything."

The Republic, Sweden and Tuesday night's opponents Austria are currently locked in a tooth and nail battle for second place in Group C with leaders Germany five points clear of the developing scramble beneath them.

In the circumstances, defeat in Dublin is unthinkable for Trapattoni's men if they are to keep alive their hopes of qualification with a tough trip to Vienna to come.

"I am very scared about him because he is a very good player" - Marco Tardelli on Zlatan Ibrahimovic

Tardelli acknowledged that the double-header could make or break their campaign.

He said: "Yes, it's normal. I think we need to get four points. It's very important to keep our qualification hopes alive."

However, asked by a Swedish journalist how he expected those points to be delivered, he said: "Three against Sweden and three against Austria."

Trapattoni and his players began work in earnest in Malahide this morning with the squad now fully assembled following the arrivals of skipper Robbie Keane and defender Darren O'Dea, with James McCarthy also arriving following his big-money deadline day move to Everton from Wigan.

Shane Long was back in training too after he made a late, but ultimately unsuccessful, dash back across the Irish Sea as Hull attempted to lure him from West Brom.

Asked if the collapse of the proposed deal would adversely affect the striker, Tardelli said: "I don't think so. I think he will be fit for the match in his mind.

"He is happy. That's football. Sometimes it happens, sometimes not."

Tardelli was adamant too that experienced defender John O'Shea would suffer no ill-effects of a mauling by club manager Paolo Di Canio after Sunderland's 3-1 Barclays Premier League defeat at Crystal Palace.

The 32-year-old, who conceded a penalty and was sent off for a mistimed tackle, was singled out for particular attention as the Italian publicly tore into his team after the game.

Tardelli said: "John O'Shea is a good boy and a good player.

"I don't know why Di Canio spoke badly about him, but John O'Shea played for many years for Manchester United. Manchester United was a good school for him."

O'Shea seems a certain starter against Sweden, and he could be partnered in central defence by Richard Dunne, who is in line to make his first competitive appearance for his country since the Euro 2012 finals after missing all of last season through injury.

However, Trapattoni still has a doubt over left-back Marc Wilson, who sat out training once again today with an ankle problem, while keeper David Forde had only a partial involvement.

The Italian must also come up with a solution to winger Aiden McGeady's absence with Tardelli hinting that strikers Jon Walters and Simon Cox, who have played previously in wide midfield berths in the green shirt, could be candidates to plug the gap.