New Zealand have beaten fierce rivals South Africa in their Rugby World Cup opener in Japan.The All Blacks, who are the favourites to win the whole competition, picked up a very impressive 23-13 victory over their Southern Hemisphere rivals.Both teams came into the game with expectations at an all-time high, with the All Blacks having won both of the previous two tournaments, and being undefeated in their previous 28 World Cup pool games - a run that has stretched back 32 years. The Springboks, on the other hand, came in with confidence at an all-time high, with coach Rassie Erasmus having completely transformed his South African side since taking over in early 2018, claiming last year's Rugby Championships from under New Zealand's nose along the way.After a frenetic build up, and particularly intense haka by the defending champions, Erasmus' Springboks took an early lead after Handre Pollard smashed a difficult penalty between the uprights with just a minute on the clock. 

After a nervy and close-fought 20 minutes followed this frantic opening, New Zealand finally registered some points of their own, as Richie Mo'unga made no mistake with a penalty of his own - smashing the All Blacks level with their Southern Hemisphere rivals. 

This then seemed to kick-start Steve Hansen's side into life, after a kick wide to the right by Mo'unga started a brilliant move by New Zealand, with Scott Barrett sending George Bridge over to finish. 

The All Blacks then struck again near immediately, with Anton Lienert-Brown this time cleaving the shaky Sringbok defence in two, before Barrett himself this time finished another fine move - Mo'unga then converted once again to give his side a commanding 17-3 lead going into the break.

With the pressure well and truly on in the second half, South Africa came out a side reinvigorated and immediately pegged their rivals back, courtesy of a fine Try from Pieter-Steph du Toit - Pollard also converting to cut the deficit to just seven points.

The All Blacks reacted by once again upping the intensity, but sloppy mistakes in the following minutes twice almost presented their rivals with a chance to level affairs.

It was a moment of inspiration from Pollard once again, however, that next saw South Africa register, after a beautiful clipped drop-goal from all of 40 metres saw the Springboks battle to within four points.

A feisty few minutes followed, with tempers flaring on both side as the intensity was dialled up another few notches, and the crowd roared their appreciation.

New Zealand were awarded another penalty in the 67th minute, with Mo'unga kicking a magnificent effort to once again stretch his side's advantage to seven. 

In the end, New Zealand did enough to get the job done.

Were New Zealand to retain their World Cup title, it would see a record-extending fourth title added to their collection of three, two of which have been won consecutively in 2011 and 2015. 

A victory for South Africa would see them draw level with the All Blacks' total of three titles, with their previous wins having coming in 1995 and 2007.