New Zealand have made it two wins from two in their Rugby World Cup campaign and cemented their place at the top of Pool C despite conceding a second-half try to Namibia in a 58-14 victory at the Olympic Stadium.

Steve Hansen made 12 changes to his side from the opening 26-16 win over Argentina and his players were far from convincing for long periods, despite keeping up their 100% record in defence of their 2011 crown.

With Dan Carter among those rested, Beauden Barrett was on kicking duty and his fifth-minute penalty started the rout before the first try of the match arrived barely 90 seconds later when Sonny Bill Williams offloaded for Victor Vito to go over in the corner.

The All Blacks had 82% possession in the opening 10 minutes and they made their dominance count again when Nehe Milner-Skudder skipped past two challenges to score, and it was three with barely a quarter of the game gone as Williams moved into space before playing a no-look offload for Malakai Fekitoa to extend the advantage.

Theuns Kotze's two penalties in reply for were greeted with enthusiasm from the crowd and Johan Tromp was denied by a last-ditch Williams challenge before Namibia shot themselves in the foot, allowing Barrett to break through Jacques Burger's tackle from a lineout and sprint home for a fourth try to earn the champions a bonus point before half time.

Namibia winger David Philander knocked on as he could not grasp the chance to intercept and score a famous try downfield, before Milner-Skudder added his second of the game to give Hansen's much-changed side a five-try 34-6 advantage at the break.

Kotze added a third penalty after the restart but the lead was extended again through Julian Savea's strength as the winger powered over after a patient move, but Namibia's golden moment arrived four minutes later.

The underdogs boldly went for touch from a penalty instead of kicking for the posts and swept the ball across the field and back again in a well-worked move before centre Johan Deysel bullied his way over the line to spark wild celebrations.

Any momentum that might have given them was stifled, however, as Jaco Engels was sin-binned for knocking the ball from Tawera Kerr-Barlow's hand as the scrum-half attempted a pass from the ruck, and New Zealand took advantage as Ben Smith scored soon afterwards.

Namibia captain Burger left the field to a rapturous reception with 15 minutes to play in recognition of a committed display as his side continued to make the All Blacks work hard, and the frustration continued for Hansen's side as Luke Romano's score was scuppered by an accidental offside.

New Zealand did finish with a flourish as Savea got them past the 50-point mark with his second of the evening and Codie Taylor added a ninth and final try as the champions secured a hard-fought victory.