KOBE, Japan (AP) — The Springboks will give some of their "bomb squad" a chance to start against Canada at the Rugby World Cup on Tuesday. That means that some of "the 15" will have to fill in on the bomb squad. And the rest of the 15 will be the "dirt trackers."

Confused?

At the World Cup, the Boks have a term for the guys who regularly sit on the bench: The bomb squad. The first-choice team is known as the 15. And the players who miss out on selection completely and are out the matchday 23 are the dirt trackers.

Those groups are all a little muddled for South Africa's last Pool B game against Canada at Kobe. Some of the 15 are due a rest after putting away Italy 49-3 only a few days ago, so the bomb squad has been called in.

Coach Rassie Erasmus had the tricky task of explaining the fairly fluid situation in the Springboks camp.

"The eight guys outside the 23 ... they're the dirt trackers, they help you to prepare for the test match," Erasmus explained. "Then you get the starting players, those are the 15.

"Then you get the reserves and they call themselves different names. We currently on this tour call them the bomb squad because they come in there (during a game) and they must fix it if it's not going well. They must come in and sort out the situation.

"It's kind of a standing joke in the team," Erasmus added, and lock Lood de Jager has been the butt of most jokes this past week.

De Jager was a founding member of the bomb squad as a regular bench-warmer for the Springboks recently. Then he won a start against Italy at the World Cup in place of Franco Mostert and lost his bomb squad status. De Jager went to join a bomb squad group hug after the Italy win at Shizuoka Stadium on Friday night and was shooed away by veteran utility back and senior bomb squad member Frans Steyn.

According to Erasmus, de Jager was told: "Lood, you're not part of the bomb squad anymore. (Franco Mostert) is now part of the bomb squad."

Steyn, loose forward Francois Louw, locks RG Snyman and Mostert and prop Vincent Koch are all bomb squad members who will start against Canada among the 13 changes the Springboks made to their starting 15.

Erasmus is balancing the need to rest those players who likely have bigger challenges to come in the quarterfinals with South Africa still needing to beat Canada, ideally with a bonus point, to be sure of making the quarters.

So, Erasmus gave his reserves a chance to start but also put front-line players such as Eben Etzebeth, Pieter-Steph du Toit, Handre Pollard and Willie le Roux on the bench — an acting bomb squad if you like — for added insurance against Canada. Captain Siya Kolisi and Damian de Allende are the only guys who don't cause any problems changing groups by starting again after running out against Italy.

"This match is just as important as the three that we have already played," Erasmus said, switching to serious mode. "It has the same number of (pool) points available and the same impact on our chances of qualifying and we have to now complete the job."

Canada has lost 48-7 to Italy and 63-0 to New Zealand in its two World Cup games and is expected to struggle again at Kobe Misaki Stadium no matter which squad South Africa fields.

But Canada winger DTH van der Merwe has said he's going to enjoy it no matter what. He was born in South Africa before his family moved to Canada in 2003. Van der Merwe has played for Canada for 13 years and has 38 tries in 60 tests, but he's never played against his country of birth before.

When he does on Tuesday, he'll break the Canadian record with his 15th World Cup appearance.

"I think there'll be some mixed emotions singing the national anthems ... I'm a proud Canadian but I'm also still a proud South African as well," he said.

Van der Merwe can also become the fifth man after Brian Lima, Brian O'Driscoll, Gareth Thomas and Adam Ashley-Cooper to score a try in four World Cups.

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South Africa: Damian Willemse, Warrick Gelant, Damian de Allende, Frans Steyn, Sbu Nkosi, Elton Jantjies, Cobus Reinach; Francois Louw, Kwagga Smith, Siya Kolisi (captain), Franco Mostert, RG Snyman, Vincent Koch, Schalk Brits, Thomas du Toit. Reserves: Malcolm Marx, Steven Kitshoff, Frans Malherbe, Eben Etzebeth, Pieter-Steph du Toit, Herschel Jantjies, Handre Pollard, Willie le Roux.

Canada: Andrew Coe, Jeff Hassler, Conor Trainor, Ciaran Hearn, DTH van der Merwe, Peter Nelson, Phil Mack; Tyler Ardron (captain), Matt Heaton, Lucas Rumball, Kyle Baillie, Evan Olmstead, Jake Ilnicki, Andrew Quattrin, Hubert Buydens. Reserves: Benoit Piffero, Djustice Sears-Duru, Matt Tierney, Josh Larsen, Michael Sheppard, Jamie Mackenzie, Shane O'Leary, Guiseppe du Toit.

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