South Africa are coming to the end of a very long season, but coach Heyneke Meyer believes the players have "one big effort" in them.
Apart from the heavy workload on the international stages, the Springboks players also had to cope with more than four months of Super Rugby and a stint at the end of the Currie Cup season.
On Saturday they are up against an England that has the benefit of players coming off a break, following the June Test window, and their domestic competitions are all still in their infancy stages.
However, despite having watched a large chunk of his squad having to sit out training this week, Meyer believes that the Boks should still have the better of their hosts at Twickenham on Saturday.
"Yes, it has been a very long season," Meyer told a media briefing at the team's base in London, adding: "We are probably the only country where the [national team's] players were involved in the Currie Cup [domestic competition].
"Most of the guys couldn't train, especially the loose forwards had lost of bumps and bruises.
"I always knew this last game was going to be a very tough game, but I really want the guys to dig deep. I need one more big effort from them."
The Bok mentor admitted that there are some concerns, given the huge attrition rate amongst a group of men that have been playing non-stop since February.
"I know they always lift themselves for England, but I am worried," Meyer said, adding: "I can see mentally, it has been a very long season.
"However, knowing these guys, they will stand up to the challenge, they want to play for their country and the guys next to them. But in terms of training we had to manage them throughout this week.
"It will take a huge effort, mentally, to get up for the last game."
The Bok coach dismissed the suggestion that he is claiming the 'underdog' tag.
"No, I won't say that," he said, when asked about the fatigue factor.
"My team knows I don't believe in excuses.
"You are still representing your country, they still have to mentally up for it and they are a really proud bunch of players.
"I always believe that if the mind is there, anything is possible.
"I won't say that England has the advantage. We could have the advantage because we have been together for longer.
"It is going to be tough, but we need to be positive going into the game."
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