RBS 6 Nations champions England were brought crashing down to earth as Ireland recorded a stunning victory at Twickenham.
The Irish ended Englands 22-Test unbeaten run on home soil in sensational fashion, a sequence that stretched back to World Cup 1999.
But the world champions could have few complaints about the result, as Ireland secured their first away win in the fixture since 1994.
Although scrum-half Matt Dawson scored a first-half try, converted by Paul Grayson, there was no disguising Irelands territorial dominance, recognised by the RBS Man of the Match award for Gordon D'Arcy.
Fly-half Ronan OGara landed four penalties and a conversion of full-back Girvan Dempseys 51st-minute try - too much for England to cope with.
Not since 1997 had they suffered a championship defeat on home soil, and the World Cup homecoming turned into a wake.
England just did not perform, despite the promptings of a capacity 75,000 crowd, and head coach Sir Clive Woodward is sure to question such a lacklustre effort.
Retired World Cup skipper Martin Johnson and World Cup match-winner Jonny Wilkinson were sorely missed and, while England should still beat Twickenham visitors Wales in a fortnights time, France away could prove beyond them.
England produced little rhythm or cohesion, being knocked out of their stride by an Ireland side who were displayed greater organisation and commitment.
It was a shocking homecoming for new England skipper Lawrence Dallaglio, but he will be the first to admit that Ireland richly deserved their win as they became the first team to beat the world champions.
England, having reeled off 10 successive victories, now have some serious soul-searching to do.
England: Balshaw, Lewsey, Robinson, Greenwood, Cohen, Grayson,Dawson, Woodman, Thompson, Vickery, Borthwick, Kay, Worsley,Hill, Dallaglio.
Replacements: Simpson-Daniel for Balshaw (52),Barkley for Grayson (58), Regan for Thompson (58),Jones for Worsley (52).
Not Used: Stevens, Back, Gomarsall.
Ireland: Dempsey, S. Horgan, O'Driscoll, D'arcy, Howe, O'Gara,Stringer, Corrigan, Byrne, Hayes, O'Kelly, O'Connell,S. Easterby, Gleeson, Foley.
Replacements: Maggs for Dempsey (60).
Not Used: Sheahan, Best, Longwell, Costello, G. Easterby,Humphreys.