Adi Jacobs, JP Pietersen, Meyer Bosman, Jean de Villiers, Schalk Burger and Andries Bekker all sat out the first day's training through injury, while Tendai 'Beast' Mtawarira was absent after sitting an exam.
Jacobs, Pietersen, de Villiers and Burger are all expected to start against the Lions in three-and-a-half weeks times, while Bekker and Mtawarira are both likely to be included in the matchday 22 against the best Britain and Ireland has to offer.
The injured players will be monitored throughout the week, with the Boks training today and tomorrow ahead of Thursday's flight to the Namibian capital of Windhoek.
Friday's fixture is the Boks' only warm-up match ahead of the first Test against Ian McGeechan's Lions on June 20 in Durban and their head coach realises his players must make the most of their time together as a squad.
"We need to use this game effectively to get the guys to gel again and to get our systems functioning," said Peter de Villiers.
"It is a bit tough without the Bulls players but we understand that they have a Super 14 final to play.
"Nevertheless the Namibian game is an opportunity for some game time for those who will be in the Springbok squad, which is important to our preparations for the upcoming British & Irish Lions series."