Giovanni Trapattoni urged his Ireland players to believe in their ability after beating World Cup qualifiers Paraguay 2-1.
While Paraguay booked their ticket to South Africa with two games to spare, Ireland were denied a place at next month's finals in a controversial play-off with France.
Yet although the South Americans had already played three warm-up matches and bossed possession, they struggled to break down the Republic defence and the hosts were more incisive in attack.
Wolves striker Kevin Doyle headed a seventh-minute opener before Stoke midfielder Liam Lawrence fired home in the 39th minute.
And although Argentina-born striker Lucas Barrios marked his Paraguay debut with a 58th-minute strike, Ireland held on to claim an impressive success.
"I told the players before the game to remember three of our last four opponents - Italy, France and Brazil," Trapattoni told Sky Sports.
"We have to remember we are a good team because we played against these teams at a good level and I think they believed me.
"The first half I saw our team play with mentality, attitude and attention.
"Second half we must forget because some players have been on holiday. We had only two days together (before the game) so maybe second half we were down and missing some strength.
"The result was important but what was more important was our performance, and I think we deserved to win."
Trapattoni handed senior international debuts to Paul Green, Cillian Sheridan and Keith Fahey off the bench in the second half.
And they may feature more as Ireland aim to follow up the morale-boosting victory by claiming another World Cup scalp on Friday, with England's Group C opponents Algeria visiting the RDS Arena.
"For us, it's important we repeat the performance," added Trapattoni.
"I said before that maybe after just two days together we wouldn't have the same strength and the same condition.
"But I have confidence with the new players today, like Paul Green for the last 30 minutes, he played well.
"I think we must now think about a few new players (against Algeria)."
Kevin Doyle was delighted with Ireland’s 2-1 win over Paraguay in the friendly international match played at the RDS in Dublin yesterday
Doyle and Liam Lawrence scored in the first half as Ireland recorded a victory against their World Cup-bound opponents.
“It’s a win, they’re going to the World Cup and we’re not so it’s a good win for us,” Doyle reflected..
“They’re going to be well trained and we beat them pretty convincingly.
“We looked pretty solid and played well.”
Paraguay pulled a goal back through Lucas Barrios in the second half and became more of a threat, with Doyle admitting the home side perhaps began to feel the pace.
“It’s been a good few weeks since some of us had a game and maybe it started to show a little,” the Wolves forward added.
“They’re the opposite and they were probably a bit sharper come the end.
“But it was a chance for us to be together again, it was another good performance and a good win.
“It all will hopefully count when the European Championship qualifiers come round.”
Ireland Manager Giovanni Trapattoni will field an experienced Ireland side in tonight’s friendly against Paraguay despite a number of withdrawals.
Shay Given, Richard Dunne, Aiden McGeady and Kevin Kilbane are missing but Robbie Keane, Damien Duff, John O'Shea and Kevin Doyle will all start.
Regulars Glenn Whelan, Keith Andrews, Sean St Ledger are also included as is Fulham defender Stephen Kelly.
With Given missing, Coventry keeper Keiren Westwood will start in goal. The twenty-five-year-old will win his fourth cap as he deputises for the injured Given and has been praised by boss Giovanni Trapattoni.
Trapattoni said: “Westwood is a goalkeeper with a great personality. Physically, he is fantastic.
“He has personality and a presence that I like very much, and I don’t think he will be fazed by the game.”
Wolves striker Doyle missed training on Sunday because of a sore throat but has been passed fit to play.
Tuesday's game and Friday's contest at the RDS against Algeria will be part of the squad's preparations for the European Championship qualifiers which start in early September with the away trip to Armenia.
