The Republic of Ireland outclassed Northern Ireland's young line-up in Tuesday's Nations Cup clash in Dublin.
Mistakes by keeper Alan Blayney and Lee Hodson gifted the Republic's opening two goals to debutant Stephen Ward and Robbie Keane.
The third goal came on the stroke of half-time as the unlucky Craig Cathcart diverted into his own net.
Keane's penalty - after Adam Thompson's harsh dismissal - increased the lead and new cap Simon Cox added the fifth.
With both sides severely understrength, Republic boss Giovanni Trapattoni handed first caps to Wolves utility man Ward and West Brom striker Cox, while Josh Carson made his Northern Ireland debut.
Ward was a late replacement for Marc Wilson at left-back while Seamus Coleman and Kevin Foley were named in the Republic midfield ahead of Liam Lawrence and Keith Fahey.
The build-up to the match had been dominated by the
continuing player eligibility row involving the two Irish governing bodies
boycott of the fixture by Northern Ireland
fans unhappy over the security regime for the encounter.
Northern Ireland were backed by only 200 fans but given the empty spaces at the Aviva Stadium, it appeared as though the majority of the Republic faithful had also opted to give the game a miss, although a number of the home fans did see fit to roundly boo the playing of God Save the Queen.
Northern Ireland made a bright start with Jonny Gorman's snapshot just wide in the second minute after a Sammy Clingan corner.
Thompson (right) was red carded for this trip on Keane
Gorman then broke clear of the Republic defence down the left flank with home keeper Shay Given apparently stranded off his line, but the Wolves youngster was unable to pick out a Northern Ireland colleague.
After a slow start the Republic began to take control and Keith Andrews fired a curling effort against the woodwork after new cap Cox had held the ball up well in attack.
Keane sped clear of the Northern Irish defence two minutes later but a heavy second touch allowed Blayney to gather at the Tottenham striker's feet.
However, Blayney was badly at fault six minutes later as he spilled a tame Treacy cross which allowed Ward to poke home from close range.
The Republic's second goal was another gift on 37 minutes as Watford youngster Hodson's dreadful back pass gave Keane more than enough time to dink over Blayney for his 47th international strike in 106 appearances.
Only a last-ditch block by Gorman prevented Coleman adding a third a minute later as the Republic threatened to run riot.
But the third goal did come, on the stroke of half-time, as the unlucky Cathcart diverted into his own net after Blayney had failed to hold Coleman's low cross.
The pain continued for the visitors after the break as a woeful Blayney clearance eventually resulted in youngster Thompson conceding a penalty and being harshly sent off.
Cathcart failed to control Blayney's sliced kick and Thompson fouled Keane as the Republic skipper was about to pull the trigger.
Keane pleaded the case for Thompson to be allowed to stay on but Scottish referee Craig Thompson was having none of it and the Spurs striker calmly netted the spot-kick to draw level with former England striker Gary Lineker's haul of international goals.
Amid the plethora of substitutions, Northern Ireland boss Nigel Worthington introduced Oliver Norwood, Niall McGinn and Liam Boyce, but the changes had little effect on the visitors.
The impressive Cox was able to waltz his way through the Northern Ireland defence before curling in the fifth goal on 80 and sub Stephen Hunt hit the woodwork in the closing moments.
Rep of Ireland:
Given (Forde 72), McShane, Ward, Kelly, Delaney, Coleman (Lawrence 55), Andrews, Foley (Hunt 70), Treacy, Keane (Keogh 62), Cox.
Subs Not Used:
St Ledger, O'Dea, Randolph.
Blayney, Thompson, Cathcart, McAuley, Hodson, Carson (McGinn 73), Clingan, Davis (Garrett 76), Gorman (Coates 55), Feeney (Boyce 73), McQuoid (Norwood 46).
Subs Not Used:
Tuffey, Winchester, Dallas, Owens.
Craig Thomson (Scotland)