Italy 20-61 Wales
Wales produced a remarkable second-half performance at Stadio Olimpico but it proved in vain on a thrilling final day in the RBS 6 Nations.
Wales went from 14-13 ahead a half-time to secure a record 60-21 Six Nations win in Rome - and North proved their attacking destroyer.
The Northampton wing powered over for a treble, while his fellow wing Liam Williams also touched down, as did scrum-half Rhys Webb, centre Jamie Roberts, skipper Sam Warburton and replacement Scott Williams.
Full-back Leigh Halfpenny kicked two penalties before going off injured, but fly-half Dan Biggar proved a capable deputy, slotting a penalty and six conversions as Wales scored 47 second-half points.
Italy scored an early Giovambattista Venditti try and a late Leonardo Sarto touchdown, with Kelly Haimona kicking a penalty and substitute Luciano Orquera adding a penalty and two conversions, but the Azzurri were ultimately horribly outclassed.
It left Ireland needing a 21-point win against Scotland to have a chance of winning the title, which they managed, leaving the Welsh effort proving not quite enough.
Wales arrived in Rome knowing that an emphatic victory was their likely requirement to keep the pressure on their title rivals.
But Wales, 21 points inferior to second-placed Ireland before kick-off and 25 behind England, made a sloppy start, conceding a penalty for obstruction inside the opening minute that Haimona landed for a 3-0 lead.
Haimona, though, was forced off injured just four minutes later, suffering an arm injury in an attempted tackle on Roberts, and he was replaced by Orquera.
Orquera then restored Italy's advantage through an angled penalty strike, but Halfpenny replied immediately, levelling the contest at 6-6.
Wales, predictably using Roberts as their main midfield attacking weapon, looked to consolidate territory, and they struck with a try after 19 minutes when Halfpenny's well-placed kick was gathered by Roberts, who finished off the move.
But Wales were rocked 15 minutes before half-time when Italy patiently went through a number of attacking phases and Venditti darted through an uncharacteristic gap in the visiting defence to score.
Orquera's successful conversion edged Italy 13-11 in front, and there was plenty to ponder for Wales boss Warren Gatland and his coaching staff, with Wales having shown little of the composure or intensity that was on show against Ireland seven days ago.
And there was further cause for concern when Halfpenny required treatment after attempting to tackle rampaging Italy number eight Samuela Vunisa, before he left the action to be replaced by Scarlets centre Scott Williams, who went on the wing and Liam Williams switched to full-back.
Wales urgently needed a settling down period as the interval approached, but with their scrum in serious trouble, there was no sign of Italy letting up with regard to their set-piece dominance, despite a Biggar penalty that secured a 14-13 interval advantage for the visitors.
Wales needed to increase the tempo considerably, and there were signs of greater urgency in their play immediately after half-time as Webb began to chase and probe in pursuit of attacking openings.
And it was Webb's opportunism that created a second try for Wales after 48 minutes, when the Ospreys number nine took a quick penalty and the supporting Liam Williams sprinted over unopposed, with Biggar's conversion making it 21-13.
Before Italy could recover, Wales struck again, with Liam Williams turning provider as he gathered a high kick, broke clear and then sent a supporting North sprinting clear to claim an easy try.
Biggar's conversion meant Wales had scored 14 points in two minutes, suggesting the game was won with more than 30 minutes left and it was a case of how many more tries they could score.
Italy then had centre Andrea Masi sin-binned as their game continued to unravel, and Wales immediately made them pay as centre Jonathan Davies sent North in for his second try, with Biggar's conversion making it 35-13.
North then completed his hat-trick when he led the Italian defence a merry dance, and Biggar's conversion took Wales 42-13 ahead with the promise of more to come.
Italy replacement lock Quintin Geldenhuys followed Masi into the sin-bin as the home side struggled to cope with wave after wave of Welsh attacks, and Wales continued pressing inside the final quarter.
Webb then added Wales' sixth try, touching down from close range, before skipper Sam Warburton sprinted clear to take Wales past 50 points.
It was breathless stuff, and a fantastic tribute to Wales' attacking adventure, with Scott Williams adding another try, which Biggar converted, taking Wales past 60 points, although Sarto's last-gasp try proved a minor blow in terms of points difference.
But the title now goes down to Ireland or France after the 30-point win for Joe Schmidt's side in Scotland.
