The call-up for Johan Grobbelaar (hooker) marks his first to the Springbok side, while Specman (wing) and Du Preez (loose forward) return after being included in the wider squad for the Castle Lager Lions Series.
Grobbelaar has been a key figure for the Vodacom Bulls in the last few seasons, and he also represented the Junior Springboks in the World Rugby U20 Championship in Georgia in 2017.
Specman, meanwhile, made his Test debut against Georgia last month as he establishes himself at international level in the 15-a-side code after a successful career with the Blitzboks.
Du Preez, in turn, was one of the unlucky few who missed out on selection for the Test against Georgia and the South Africa ‘A’ match after Testing positive for COVID-19.
“We have a tough Castle Lager Rugby Championship series ahead after Saturday’s series decider against the British & Irish Lions and given the strict COVID-19 protocols we have to adhere to, we have decided to bring the players in sooner rather than later,” said Nienaber.
“This is Johan’s first senior national call up and we are looking forward to seeing what he can do at this level after showing his class and consistency at the Bulls.
“Rosko played against Georgia and we know what he has to offer having worked with him for several weeks before he was released from camp.
“Dan was one of the unlucky players who didn’t get game time due to COVID-19 in our first few matches, so we are looking forward to having him back and giving him a chance to show us what he can do again.”
They join Duane Vermeulen (No 8) and Jaden Hendrikse (scrumhalf), who were the other two additions to the team.
The Springboks will face against the British & Irish Lions in the third and final Test in Cape Town on Saturday and then travel to Nelson Mandela Bay on Sunday for the first two Tests in the Castle Lager Rugby Championship against Argentina on 14 and 21 August respectively.