South Africa kicked off the defence of their Rugby World Cup title with an 18-3 victory over Scotland in the teams' opening Pool B match in Marseille on Sunday.

The Springboks, featuring 14 of the match-day squad of 23 that beat England in the 2019 final, were made to work hard for the win, with just two Manie Libbok penalties to show for their first-half graft, Finn Russell pulling one back for Scotland.

A brace of tries within three minutes from Pieter-Steph du Toit and Kurt-Lee Arendse early in the second period, however, turned the game.

It was the first time South Africa have won their first match at a World Cup since they edged out Wales 17-16 in 2011, having then gone on to opening-game defeats by New Zealand in 2019 and Japan four years earlier.

The victory also extended the Springboks' winning run over the Scots to eight and maintained their record of having never lost to them outside of Scotland.

In balmy Marseille conditions at a packed Stade Velodrome, Jacques Nienaber's team played the long game before putting Scotland to the sword for the third time at the World Cup pool phase after previous victories in 1999 and 2015.

After winger Duhan van der Merwe was twice pounded by Bok skipper Siya Kolisi tackles, it did not take long before the defending champions showcased their fearsome scrumming power, Zander Fagerson penalised for collapsing.

Libbok pushed his penalty effort wide of the posts but made up for that miss minutes later when Russell was blown up for a deliberate knock-on.

When a massed Scottish defence bundled Damian de Allende into touch as the Boks pressed, the crowd erupted with cries of "Scotland! Scotland!", players piling in from all quarters to get some of the off-pitch push and shove.

South African winger Cheslin Kolbe, for all his dancing feet, produced a devastating hit on Sione Tuipulotu and with Malcolm Marx quick into the ruck to force a turnover, the Australian-born centre was penalised.

Libbok stroked his second penalty over in a tight game with neither side in the ascendancy.

Darcy Graham botched Scotland's best chance of the first half, the winger feinting a pass rather than better utilising a clear three-on-one chance down the left wing, with try-scoring machine Van der Merwe outside him.

Scotland got two of their own scrum penalties to relieve some pressure, the second within kicking distance of the posts for Russell, who made no mistake to make it 6-3 and very much alive at half-time.

Libbok missed a long-range penalty early in the second period as the Boks pressed anew, a smart RG Snyman offload giving Arendse a metre of space.

While Blair Kinghorn was in place to snuff out that attack, the ball was recycled and worked left to Du Toit, who muscled his way through three Scottish defenders to dot down.

Libbok's kicking misery continued as he missed the conversion, but he made amends for that just moments later.

A blitz defence nullified a rare Scot attack, allowing Jasper Wiese to counter ruck. When Libbok received the ball at first receiver, he produced a no-look, inch-perfect cross-kick to Arendse.

The Bok winger caught the ball going at full tilt and had a clear run-in to the corner, Faf de Klerk taking over kicking duties and duly converting from the touchline to make it 18-3.

De Klerk missed a penalty of his own, but from that point the Springboks locked it down to secure a comfortable win as they bid for a record fourth World Cup title. (AFP)