Besieged by their media's obsession with the so-called "biscotto" conspiracy theory and concerned at their goal-shy performances in draws with Spain and Croatia, they delivered all that was required with a solid, if not commanding, 2-0 win.
Goals in each half by Antonio Cassano and substitute Mario Balotelli, both from corners by the evergreen Andrea Pirlo, took Italy through to the last eight along with group winners Spain, but it was anything but an easy ride.
"It has been a very difficult match, we came up against a team that made us suffer," said Italy coach Cesare Prandelli.
"Today, we knew that heart mattered more than quality. Tonight we created a lot... I hope it will be like this also in the next match."
But Italy, galvanised by Prandelli, a former player under Trapattoni, now 73, at Juventus and a serious student of the Italian coach's career, proved themselves capable not only of surviving a lively start by the Irish, but finding the cohesion to take control and fashion chances.
Having reverted to the 4-4-2 formation that served them well in the qualifiers, Italy were ready for Ireland's aggressive approach, but needed goalkeeper Gianluigi Buffon to make key saves before Cassano's 35th-minute header put them ahead and again in the closing stages before Balotelli cleverly volleyed the second.
Their euphoria on the field after the final whistle, when news arrived of Spain's 1-0 win, was as much an expression of relief as celebration, but signalled that under Prandelli this team has built up a unity and sense of purpose that the 'Trap' himself would be proud of.
Prandelli's man-management and team selection - he made four changes from the side that had started the 1-1 draw with Croatia - were both spot on for
