Gupta-owned Oakbay Investments has questioned the timing of Finance Minister Pravin Gordhan’s legal .
Having already sewn up the series by winning the first two games by 93 runs and 61 runs, the Proteas will offer the pair an opportunity to impress as they consider their squad options for next year's World Cup in Australia and New Zealand.
While Rossouw will come in for Hashim Amla, who has returned to South Africa for a short period of rest before next week's triangular series against Zimbabwe and Australia in Harare, Shezi will replace one of the seamers from the first two matches.
Fast bowler Marchant de Lange could also return to the South African side for the first time since March 2012, having overcome a frustrating series of injuries.
"There's lots for them to gain, I think," Proteas captain AB de Villiers said. "They've played a lot of cricket of late so they're all in decent form.
"The fact that they're here means that they're in good form so I don't think that there will be too much pressure - I'll speak to them and try and free them up a little so they can express their talent."
Both Rossouw and Shezi came into the South African squad on the back of excellent showings with the A side in Australia recently.
While Rossouw scored a century and two 50s in a quadrangular series, Shezi caught the eye when he took 2 for 26 in 10 overs against India A and then 6 for 42 against Australia's National Performance Squad.
While the presence of two debutants in the South African side will give Zimbabwe hope that they could be more competitive on Thursday, the hosts know that they must show marked improvement with the bat.
The top order has been particularly poor, collapsing to 34 for three in the first game and 59 for five in the second.
"The guys are a little bit loose up front," said Sean Williams, who scored 50s in both matches.
"It is a little bit upsetting because we played against Pakistan, who to me have got a really serious bowling attack, and we batted really well against them.
"I don't know whether it's application or value of wickets. I'm not sure what's going on."
Zimbabwe: Elton Chigumbura (capt), Brendan Taylor, Hamilton Masakadza, Vusimuzi Sibanda, Sean Williams, Richmond Mutumbami, Luke Jongwe, Prosper Utseya, John Nyumbu, Shingirai Masakadza, Malcolm Waller, Timycen Maruma, Neville Madziva, Sikandar Raza Butt, Tafadzwa Kamungozi, Tinashe Panyangara, Brian Vitori
South Africa: AB de Villiers (capt), Kyle Abbott, Quinton de Kock, Marchant de Lange, JP Duminy, Faf du Plessis, Imran Tahir, Ryan McLaren, David Miller, Wayne Parnell, Aaron Phangiso, Rilee Rossouw, Mthokozisi Shezi