Jordan Larmour scored a superb treble on his first start in the green shirt as Ireland found their stride in the second half to crush Italy 54-7 in Chicago.
Tadhg Beirne dived over in the fifth minute to give an experimental Ireland a perfect platform but they failed to build on it for the next half an hour.
Italy had had plenty of the play, and spurned some decent chances, before full-back Larmour, who had won his previous six caps off the bench, showed great pace to set up Luke McGrath for Ireland's second try on 34 minutes.
Italy hit back with the last action of the opening period as Michele Campagnaro read fellow captain Rhys Ruddock's pass and touched down for an intercept try and a 14-7 margin.
Joe Schmidt, watching from Ireland, would have been reasonably happy with his fringe players' defensive efforts but not their lack of attacking fluidity.
However, that all changed in the second half as Ireland cut loose and ran in six more tries, with Joey Carbery 5 from 5 with his conversions.
Beirne was again quick off the mark to score after he, Conan, Jack McGrath and Quin Roux had worn down Italian resistance and Larmour intercepted a deflected Italian pass to make it 28-7 by the 46th minute.
Replacement Sean Cronin finished off a well-worked rolling maul just before the hour and then Larmour superbly took his second try.
Garry Ringrose drew two tacklers and set his Leinster teammate away but the 21-year-old still had two men to beat. Showing superb footwork, he danced around Braam Steyn and full-back Luca Sperandio to touch down.
Ringrose got on the scoresheet himself in the 67th minute after combining with Bundee Aki. Ross Byrne, on for his debut cap along with Ulster's Will Addison, kicked a tricky conversion.
Ireland still wanted more and, with the clock in the red, Larmour sealed his hat-trick with the best of the lot.
The full-back picked up the ball inside his own half before jinking and swerving his way past four despairing tacklers in blue shirts to seal a memorable first full 80 minutes for Schmidt's side.
Ireland: J Larmour, A Conway, G Ringrose, B Aki, J Stockdale (W Addison 61); J Carbery (R Byrne 61), L McGrath (J Cooney 64) J McGrath (D Kilcoyne 50), N Scannell (S Cronin ht), A Porter (F Bealham 56), T Beirne (D Toner 61), Q Roux, R Ruddock, J Conan, J van der Flier (J Murphy 66)
Italy: L Sperandio; M Bellini, M Campagnaro, L Morisi, G Bisegni; C Canna (I McKinley 61), T Tebaldi; N Quaglio (C Traore 22), L Bigi (O Fabiano 64), T Pasquali, (G Zilocchi 61) M Fuser, G Biagi ( F ruzza 56) J Meyer, R Giammarioli, B Steyn
Referee: N Owens (Wales)