Argentina spoiled the party as international football returned to Lansdowne Road, with a controversial goal from Angel Di Maria giving the visitors a 1-0 win.
The winger lobbed Shay Given after 20 minutes at the new Aviva Stadium, but was he offside when Gonzalo Higuain flicked on Sergio Romero's goal-kick.
Despite the loss, there was still enough to please Giovanni Trapattoni as he recovers from stomach surgery in the Mater Hospital, notably an impressive debut from substitute Keith Treacy.
The Italian will not worry too much about losing momentum for the opening European Championship qualifiers if, as expected, he is fit enough to take his place on the bench.
Following a rousing pre-match reception, Keane endured a tough night on the pitch, but could have made up for it if he had not uncharacteristically spurned a late chance.
The streets around Ballsbridge and Sandymount thronged with green before the game as international football turned to Dublin 4.
With Marco Tardelli replacing Trapattoni in charge, Ireland worked hard but could not provide the guile to match the endeavour.
Messi gave the 45,200 fans a glimpse of his talents as early as the ninth minute when he skipped past John O'Shea, but his lob sailed over the bar.
His opposite number had his first shot in anger moments later, but could not find the target after Cillian Sheridan, who replaced Kevin Doyle, had out-jumped Javier Mascherano and Martin Demichelis.
Ireland were fortunate not to go behind in the 14th minute when Paul McShane was caught out by Mascherano's cross-field pass. Fortunately, the defender recovered to block Di Maria's cross.
But Ireland did not heed that warning and fell behind on 20 minutes, albeit in controversial circumstances with an offside in the build-up to the goal.
O'Shea went missing as Higuain flicked on Sergio Romero's goal-kick to Di Maria, who was standing in an offside position. The winger lifted the ball over a stranded Given as Ireland waited for a flag that never came.
Ireland improved after the restart and two quick touches from Keane took him past Demichelis on backline, but his cross evaded Fahey and Sheridan.
However, at the other end, Messi picked out substitute Diego Milito and Dunne and O'Shea scrambled to snuff out the danger.
The crowd welcomed on Andy Keogh and Greg Cunningham for the tiring Sheridan and Kevin Kilbane.
After more changes from both sides, Damien Duff drew a comfortable save from Romero following Keane's lay-off. The effort seemed to lift a crowd that had grown weary with Argentina's grip on possession.
Given was a spectator for much of the second half but got down to stop powerful drive from Fernando Gago.
The numerous substitutions broke up the pattern of the game, but Treacy's late cameo offers hope for the future.
He was straight into the action as he raced down the left wing, his cross found Andy Keogh at the front post, but the striker could only divert the ball over the bar.
Ireland pushed hard for an equaliser in a frantic final five minutes. The chance to cap a perfect night for Keane came and went when he missed an attempted overhead kick with the goal at his mercy.
Republic of Ireland: 1 Given; 2 McShane, 4 O'Shea, 5 Dunne, 3 Kilbane (20 Cunningham '57); 7 Fahey (18 Treacy '77), 6 Green, 8 Andrews (15 Gibson '68), 11 Duff; 9 Sheridan (17 Keogh '57), 10 Keane.
Ireland defender Marc Wilson revelled in his new-found responsibility at Portsmouth and insisted: I want the captaincy for keeps.
The County Antrim born Irishman was the surprise choice to lead Steve Cotterill's strongest side out for the pre-season friendly against Fulham last Saturday.
Despite being only 22, he was given the nod ahead of the likes of more senior players Michael Brown, Richard Hughes, Hayden Mullins, Tommy Smith and David Nugent.
For Wilson, it's recognition of the growing maturity from a player who in 12 months has established himself as a first-team regular.
The home-grown talent, who also skippered Pompey in Edmonton, has been one of four captains used during seven pre-season matches.
Wilson has also been called into Giovanni Trapattoni's Ireland squad for the friendly international against Argentina next week.
But Wilson is determined to cling on to that armband for Saturday's Championship opener at Coventry.
He said: 'The manager has been really good. He's just happy for me to go and play my game.
'He hasn't actually given me a reason why he's made me captain a couple of times during the pre-season.
'But I'm happy to accept the responsibility.
'I think it's a good chance for me and I think it will help me as well.
'It will help me mature as a player. It's giving me that responsibility of telling the other players what to do, talking to them, trying to gee them up.
'It's definitely a good opportunity for me and a bit of recognition, if you like.
'The captaincy means a lot to me because I love the club – I've been here seven years.
'I love doing it to be honest. I've been with this club since I was little and it's a privilege, it really is.
'I do a lot of talking and have been getting a sore throat shouting too many times! But it's all good and I'd love to keep it for the Coventry game.
'I just hope the players listen to what I am saying.'
Wilson grabbed the match-winner against Fulham during unquestionably Pompey's best performance of the pre-season.
Buoyed by the return of the likes of Kanu, John Utaka and Prince Boateng – plus Ibrahima Sonko's debut – it was a timely shot in the arm ahead of the trip to Coventry.
And Wilson is looking for Pompey to carry that form into the season ahead.
He added: 'I think that Fulham performance was probably the best of the pre-season, especially as it was against Premier League opposition.
'Fulham are a good team, they did really well last year and had a strong team out.
'We always knew it was going to be a difficult game – so to get the result was even better.
'To be honest, the trip to America took it out of the lads a little bit with all the travelling.
'Even when we came back we were jet-lagged for a long time, especially for the Bournemouth game when the lads were still struggling with it.
'I think we are now all getting back and that showed against Fulham.
'I'm looking forward to the start of the season now.
'There are some tough games ahead and we have to be ready for them.'
Wolves insist Stephen Hunt will return as good as before after dismissing fears of his injury.
The 28-year-old Ireland international completed his £3m move to Molineux yesterday on a three-year contract, despite being in rehabilitation for a damaged foot sustained against Wolves at the end of January.
Both the club and Hunt, who attended his press conference on crutches, steered away from setting comeback dates apart from confirming he will miss the first few games of the season.
Wolves’ concerns at Hunt’s injury – he had to have a ligament re-attached to his foot – and the subsequent price were believed to have been factors in the delay in getting the deal done.
But chief executive Jez Moxey and the club are satisfied Hunt will make a full recovery.
He said: “I accept that it’s unusual for players to be bought when they’re injured. But we’ve tracked Stephen for a very long time. He’s doing well in terms of his rehabilitation.
“Hull have been very open in providing us with his medical records and the surgeons who performed the operation are very satisfied with the rehab and progress he’s making.
“There are no complications. It’s just a question of time and Stephen will play when he’s ready.
“He started work with us yesterday and has been working out in the anti-gravity treadmill.”
Hunt initially played on for three weeks with painkilling injections, after initial x-rays revealed no damage and he didn’t see a foot specialist at the time.
But, when the pain continued, the Republic of Ireland international eventually underwent an exploratory operation which showed some damage, and a little bone was pinned.
He said: “I wouldn’t say it was mis-diagnosed, but it took a bit longer than expected.
“But I had an x-ray in my medical which showed everything is in place – Wolves wouldn’t have signed me without having a good look at that.
“People only need to look at my Prozone statistics and that will tell you enough.
“I know what I’m capable of and where I want to get to and I’ll make sure I get there.
“I’ll miss the first few games of the season. Hopefully it won’t be too many but for the next two months, I’m going to be working tirelessly.
“Everyone is happy and I’m over the worst of it now.”
Stoke City and Ireland midfielder Liam Lawrence has set his sights on a summer move away from the Potters to join Wolves.
The 28-year-old has dropped down the pecking order at the Britannia Stadium and is keen to move on to try and secure more regular first-team football and secure his future on the international stage.
He told the Sunday Mercury: "He (Mick McCarthy) gave me my chance when he signed me from Mansfield Town for Sunderland.
"He's a great manager and he's done an amazing job this year keeping Wolves up.
"I've spoken to the manager (Tony Pulis) and told him that I think it's best if I move on.
"If I'm not playing regularly the Ireland manager, he's not daft, he's going to know that I'm going to be rusty and he's not going to take a chance on me."
Lawrence has been an integral part of Goivanni Trapattoni’s Ireland squad over the last two years and played an important role in the central midfield position during the last World Cup qualifying campaign.
Lawrence joined Stoke in November 2006 and has gone on to score 24 goals in 125 appearances in all competitions.
Everton defender Seamus Coleman says his new four-year contract is proof he is progressing at Goodison Park.
The Donegal born Ireland u21 international is currently on loan at Blackpool and joined Everton from Sligo in 2008.
"I was playing to get a new contract because it shows that you've done alright, so I'm delighted," Coleman said today.
"When I came here I had a long enough contract but you always want to get another one to show that you've done something to earn it."
The Ireland Under-21 international's loan at Blackpool ends on Monday, the day after their Wembley play-off final against Cardiff.
But Coleman said he would think about going out on loan again.
"I'd be open to it and I'm going to do whatever David Moyes tells me to do," said Coleman. "He's the boss and whatever he thinks is right for me I'll do.
"He hasn't got a bad record with young players so far. So whatever he thinks best, I will agree with."
