Burger is currently suffering from a calf injury that saw him miss the final three weeks of the Super 14 season.
The former IRB World Player of the Year has been unable to train fully with the Springboks and is considered a serious doubt for Saturday's first Test in Durban.
Brussow was the Cheetahs' star performer when they came close to upsetting the Lions in Bloemfontein.
The 22-year-old caused havoc at the breakdown, leading many experts to criticize his original exclusion from the Springbok set up.
Brussow won his only Test cap as a replacement during November's crushing win over England and South Africa head coach Peter de Villiesr has made it clear that there is no guarantee he will add to that tally during the three-match Test series against the Lions.
De Villiers places a huge amount of faith in Burger and will therefore give him plenty of time to prove his fitness. Even if Burger is eventually ruled out of contention, Brussow is by no means favourite to start at the ABSA Stadium, with de Villiers likely to call on Blue Bulls back row Danie Rossouw.
"We brought in Heinrich Brussow in case Schalk won't make it but it is only precautionary," said de Villiers.
"Schalk is one of the players that play a major role in my plans and I build almost 60% of whatever we do in the forwards around him so it will be a big blow for us if he doesn't make it, but I am positive that he will make it."
Brussow himself has made no comment on his chances of being involved against the Lions but he has explained his delight at being called up to the now 29-man squad.
"I was at home studying when the call came," said the former Grey College student.
"I immediately called my parents and my girlfriend to tell them and they were over the moon.
"I was disappointed to miss out on selection into the original squad, which has a lot of great players, but I am very happy about being called in."
