Dublin delight for six-goal Germany
Doubles by winger Marco Reus and substitute Toni Kroos together with a Mesut Ozil penalty and a Miroslav Klose strike saw the irrepressible Germans inflict Ireland's heaviest home defeat since they lost 5-0 to Spain in December 1931.
Germany have a perfect record after three games and lead the group by three points from Sweden, who had to come from behind to beat the Faroe Islands 2-1 away and have a game in hand.
Joachim Low's Germany side, who won their 10 Euro 2012 qualifiers but lost in the semi-finals, were below their best in the opening two games of this campaign but their record of never losing an away World Cup qualifier was never in doubt on Friday.
"There was not enough pressure from them but we have also become better than in the previous couple of matches," Low told German television channel ZDF.
"We were disappointed by the Italy defeat at the Euros. There was a short pre-season preparation but we are getting more dynamic, stronger. Now we have the game against Sweden then we will have 12 points."
Ireland, having needed two goals in the final two minutes to escape from Kazakhstan with a 2-1 win last month, held their own early on but, as is often the case with Giovanni Trapattoni's defensive side, were unable to carve out any chances.
Reus, unlucky not to be awarded a penalty on the half-hour, punished Ireland's lack of enterprise from close range in the 32nd minute, starting the rout with the game's first chance.
The winger struck again within eight minutes, finishing off a fluent counter-attack, this time with a fine left foot drive from just inside the box.
Ireland, missing six senior players through injury including captain Robbie Keane and central defensive partners Richard Dunne and Sean St Ledger, fielded just four of the side who started their opening Euro 2012 game against Croatia.
Just like in their 4-0 thrashing by Spain at the Euros, the gulf in class was badly exposed for a team including many players from the lower reaches of England's top flight.
Germany, without injured central defender Mats Hummels and suspended captain Philipp Lahm, made it 3-0 after 55 minutes with Ozil notching his fourth goal of the campaign from the penalty spot after Klose was hacked down by Darren O'Dea.
Germany, who had won only one of their previous five games with Ireland and drew the last time they met in a qualifier in Dublin five years ago, were 4-0 ahead three minutes later when Klose scored his 65th international goal from a tight angle.
Kroos got the pick of the bunch for the three-times world champions just after the hour, volleying into the bottom corner from just outside the box and made it six in the 83rd before Andy Keogh got a late consolation for the embarrassed hosts.
"It's a massive humiliation. There's a way to lose a match and that wasn't the way to lose a game." Ireland's stand-in captain John O'Shea told Irish broadcaster RTE.
Ireland travel to the Faroe Islands, who prop up the group, for their next qualifier on Tuesday.