Coach Jacques Nienaber says cool heads will decide the day when the Springboks, featuring seven forwards on the bench, tackle Ireland in a crucial Rugby World Cup clash on Saturday.

Last night, Nienaber announced the 23 players who will face Ireland in the Pool B match, confirming a return to the seven-one split between replacement forwards and backs.

Scrum-half Cobus Reinach, who can double as a wing, is the Boks’ only backline replacement, as veteran playmaker Willie le Roux has been left out entirely.

There are three potential back row replacements in Deon Fourie and Marco van Staden, who also cover hooker, and Kwagga Smith, who can provide extra backline cover if needed, given his sevens experience.

“Obviously, people look at it and say it’s a risk, but for us, it’s a calculated risk,” Nienaber said.

“There are guys on that bench who cover various positions, but that is not something I’d like to go into too much because it is probably more tactical. I don’t want to talk too much about tactics. We have a lot of versatility in the squad and we showed that on the weekend by playing four [scrum-halves, against Romania]. But we are comfortable with the risk we are taking.

“Like any team selection, we went with that because we believe that’s the best way for us to make sure we get a result on the weekend.

“We always try to be as physical and intense as possible. We always say you can’t plan for a good start, but you can always plan for an intense start. We will definitely try to be as intense as possible from the start, as I think they would as well.”

It is the second time that the Springboks have used the seven-one split, which worked to great effect in the record-breaking warm-up win over New Zealand at Twickenham.

“The bench had a big impact, not only in that game but also on the weekend [against Romania],” said Nienaber.

“We analysed Ireland and after looking at them and what they bring and what we think we will need in this specific game from a tactical point of view and trying to counter everything they do – that’s the reason we went with seven-one.

“I don’t think necessarily Ireland and New Zealand are similar in how they do things. It’s for this specific game.”

Nienaber said calm heads are needed to bring the Irish’s 15-game winning run to an end.

He said in terms of player experience, the sides are evenly matched.

“Will we be able to handle the pressure they put us under? There will be ebbs and flows in the game. Will they be able to handle the pressure that’s on them? Because at the end of the day, this is an important game for both teams.

“It’s only the third game of the pool, but if Ireland slip up in this game, their Scotland game becomes massive. [If] we slip against them in this game, our Tonga game becomes massive.”