Ireland assistant coach Mike Catt has laughed off the idea that there might be collusion with Scotland to ensure both teams go through to the World Cup quarterfinals at the expense of defending champions South Africa.All three teams are still in the hunt for a knockout spot with the Springboks having completed their four Pool B matches and Ireland and Scotland meeting in a Paris showdown on Saturday.

If Scotland win by 21 points or more with the Irish earning a bonus-point, then those two teams would advance and knock out South Africa.

Springboks coach Jacques Nienaber said on Sunday that collusion would constitute "match-fixing" but Catt dismissed the idea out of hand in any case.

"That stuff is just white noise in the background. No, we are not going to be in cahoots with Scotland," he told reporters in Tours on Tuesday.

"Would we want Scotland to beat us by 21 points? Would you want Scotland to beat you by 21 points?"

Ireland, who have won their last eight tests against Scotland going back to 2017, are strong favourites to go through after their epic 13-8 victory over the Springboks at Stade de France two weeks ago.

South African fans should be reassured by the fact that the last time Scotland beat Ireland by 21 or more points was a 32-10 victory in the 2001 Six Nations, one of only six Scottish wins in 30 tests against the Irish this century.

Scotland could also go through with South Africa by winning by eight points or more on Saturday and depriving the top-ranked Irish a bonus point.

Even that has proved out of reach for the Scots in the last 22 years as the last time they managed a win with more than a seven-point margin was in a 2007 World Cup warm-up.