Scotland assistant coach Jonathan Humphreys insists his team are not gambling with their World Cup hopes, after accusations they are putting out a second string line-up against South Africa.

The Dark Blues can all but clinch a quarter-final slot if they become the second Pool B team to beat the Springboks when they clash at Newcastle's St James' Park.

But Vern Cotter has again tinkered with his team ahead of facing Heyneke Meyer's men, making a raft of changes.

Kelso's Ross Ford is amongst those left out, along with Al Dickinson, Mark Bennett and Sean Maitland - all key performers for the Scots in their opening two victories over Japan and the United States.

Ross Ford training at St James' Park. Credit: Owen Humphreys/PA Wire/Press Association Images

Cotter is also without injured duo Finn Russell and John Hardie and in all, seven members of the starting XV to face the two-time former winners are not regarded as the Kiwi's first picks.

But Humphreys says they're not sacrificing their chances against the Boks in order to stay fresh for their final - and potentially decisive - group game with Samoa.

I don't understand why people are saying it's a second string. What hasn't been written is that international rugby is a hugely, hugely physical sport.

Scotland assistant coach Jonathan Humphreys

Scotland have struggled to deal with the driving maul and they now take on a side who have got the technique down to a fine art.

Centre Matt Scott says it's going to be a big challenge:

That's the game right there - the line-out and the mauls.

Matt Scott, Scotland team