New Zealand were made to work hard in Rome before completing an ultimately comfortable win over battling Italy.
The All Blacks led narrowly by 13-7 at half-time, with Kieran Read's try drawing an Italian response through Alberto Sgarbi.
New Zealand had to wait 13 minutes for their first points, which came courtesy of Aaron Cruden's close-range penalty.
But their first try soon followed when a fast-flowing move ended with Conrad Smith scooping a loose ball and sending No 8 Read over. Cruden converted and soon added his second penalty.
A promising position for Italy slipped away when Mirco Bergamasco could not find Tommaso Benvenuti, but they came again and their pack set up a first Test try for Sgarbi. Luciano Orquera converted.
A crucial tackle from Bergamasco, helped by Simone Favaro, prevented Hosea Gear going over in the corner as Italy stayed in touch at the interval.
But a deliberate knockdown after a brave goal-line stand allowed Cruden to extend the lead five minutes after the restart and wonderful passing then sent Nonu barrelling over for his side's second try. Cruden's routine kick made it 23-7.
The Azzurri enjoyed a spell of attacking field position and Orquera's drop-goal took them into double figures. But as they sought to build up a head of steam, their handling became sloppy and knock-ons twice checked their momentum.
And having battled so hard, they allowed replacement Jane to stroll in far too easily and put New Zealand out of reach at 30-10 with 11 minutes to go. Luke McLean was credited with first contact on a bouncing ball to deny Cruden a try but Savea dived over in the left corner shortly afterwards, despite losing a boot in the build-up.
Cruden missed for the first time but strong running from Jane sent left-winger Savea coasting in behind a tired defence for a converted score to make it 42-10.