By Nick Said

NAGOYA, Japan (Reuters) - Elton Jantjies does not believe South Africa need to change their approach for Saturday’s Rugby World Cup Pool B encounter with minnows Namibia in Toyota City, they simply need to execute their plans better instead.

The Springboks lost their opener 23-13 to New Zealand in Yokohama, a game in which they had the greater territory and possession, but not the precision to hurt the defending champions.

Coach Rassie Erasmus is likely to field a much-changed line-up for the African Derby, with Jantjies taking over from Handre Pollard at flyhalf as key players are rested ahead of a crunch meeting with Italy on Oct. 4.

Jantjies has spent the last five seasons playing for Japanese club NTT Shining Arcs and so feels more at home than most in the Bok set-up.

"What we need to improve are actually the things we are usually good at, like our kicking game, defence and aerial skills, all things that we have really developed a lot over the last two years," Jantjies told reporters in Nagoya on Tuesday.

"Instead of getting 6/10 we need to get 8/10 or 9/10.

"There were a lot of swings in that game against the All Blacks, a lot of ball possession and territory, but two aerial opportunities and they got the ball back, moved into space and scored tries.

"We had the same situations but we didn’t finish, that was the difference between the sides."

Jantjies adds that rather than dwelling on the negatives from the defeat, the Boks are focused only on what is to come and how to get better.

"There were a lot of positives to build on as we look ahead to Namibia. We want to improve on our systems and keep growing as a team (in the tournament).

"We are working hard every single day on those small things and to make sure we improve on the things we are good at and not look at the negatives."

A number of the Namibia players have strong ties to South Africa and many spent their formative rugby years playing in the country.

Jantjies says there will be no mystery on the part of either team as to how they will play and what their capabilities are and that it will simply come down to execution and effort.

"It is an African derby against boys who played Super Rugby and Currie Cup in South Africa, so they will want to try and prove something. We will have the pitch up physically and mentally for the match," he said.

(Reporting By Nick Said; Editing by Amlan Chakraborty)