Tokyo - Coach Rassie Erasmus knows that the Springboks will start as favourites against Namibia on Saturday, but he also believes that the gap between the top and second tier nations is shrinking. 

The Boks have made no less than 13 changes to their starting line-up following last weekend's 23-13 loss to the All Blacks in Yokohama, with only wing Makazole Mapimpi and centre Lukhanyo Am keeping their places. 

South Africa need to win all three of their remaining pool matches to book a place in the tournament quarter-finals, but they will be expected to do that without too much trouble against Namibia, Italy and then Canada. 

"This gives us an ideal opportunity to rest guys who are vital for us in the big, big games," said Erasmus, eyeing a possible quarter-final match-up with in-form Ireland.

"It is a 'nice-to-have', and it covers a few things for us and gives us proper game time for other players."

Erasmus added that he would probably give Bongi Mbonambi a "proper start of 50-70 minutes" and then move captain and No 8 on the day, Schalk Brits, to his more familiar role of hooker.

"To have 31 guys here for what will hopefully be an eight-week tournament for us, you have to try and rotate your hookers," said Erasmus.

Erasmus added that he was expecting a physical challenge from South Africa's neighbours.

"If we play to our full potential, we should win those games," he said, also referring to the other Pool B match against Canada.

"You don't get 100 points, 80 points and 70 points anymore - it's been shown in the first week."

Kick-off on Saturday is at 11:45 (SA time). 

Teams:

South Africa

15 Warrick Gelant, 14 Sbu Nkosi, 13 Lukhanyo Am, 12 Frans Steyn, 11 Makazole Mapimpi, 10 Elton Jantjies, 9 Herschel Jantjies, 8 Schalk Brits (captain), 7 Kwagga Smith, 6 Francois Louw, 5 Lood de Jager, 4 RG Snyman, 3 Vincent Koch, 2 Bongi Mbonambi, 1 Tendai Mtawarira

Substitutes: 16 Steven Kitshoff, 17 Thomas du Toit, 18 Eben Etzebeth, 19 Siya Kolisi, 20 Franco Mostert, 21 Cobus Reinach, 22 Damian de Allende, 23 Cheslin Kolbe

Namibia

15 Johan Tromp, 14 Chad Plato, 13 JC Greyling, 12 Peter John Walters, 11 Lesley Klim, 10 Cliven Loubser, 9 Eugene Jantjies, 8 Adriaan Booysen, 7 Muharua Katjijeko, 6 Thomasau Forbes, 5 Tjiuee Uanivi (captain), 4 Johan Retief, 3 AJ de Klerk, 2 Louis van der Westhuizen, 1 Desiderius Sethie

Substitutes: 16 Obert Nortje, 17 Andre Rademeyer, 18 Johannes Coetzee, 19 Prince Gaoseb, 20 Janco Venter, 21 Wian Conradie, 22 Helarius Axasman Kisting, 23 Johan Deysel