O’Connell says Nienaber’s positive influence at Leinster is being felt in the Irish squad.
“They have added another level to how they defend and how they think about the game in the last year with Jacques, and that’s been a brilliant addition to them,” explained the former Ireland second row.
“I think it helps our players in that one of the things I notice for us is that the better the coaching in the provinces, the better the players are coming in to us.”
Ireland, meanwhile, are aiming to build on their Six Nations success after a period of some change in personnel, including the retirement of long-time captain and talisman Johnny Sexton.
Only a one-point defeat by England at Twickenham denied them a second consecutive Grand Slam.
“We had a bit of a turnover of players, Johnny in particular moving on,” said the Ireland forwards coach.
“We would have loved to have won the Grand Slam. We could have done it, we mightn’t have deserved to have won it, but we could have done it.
“But going on to win the Six Nations, especially with a little bit of turnover in the team, was excellent.”
The squad’s attention is now firmly on the forthcoming challenge.
“It’s funny how the game goes, the boys really celebrating any victory they have with any team, but you’ve got to move on quickly then and the next thing becomes the biggest, most important thing ever,” added O’Connell.
“We’ve never won a Test series in South Africa. As an Irish team we’ve only ever won one game down here, so this is a brilliant place for this team to be now.”
