Griquas coach Pote Human has made four changes to his side for the second-leg Currie Cup promotion/relegation match against the Pumas in Nelspruit on Friday.
The Kimberley-based side will travel to the Mbombela Stadium without stalwart lock Jaco Nepgen, who suffered a knee injury against the Pumas in the first-leg home clash last Friday.
Griquas will instead have the scrumming power of veteran Lourens Adriaanse who been cleared to play after injuring a stomach muscle.
"It is a huge relief that Lourens can play, but at the same time a big loss that Jaco can't," Human said.
"He has been one of our stalwarts especially in the lineouts and driving mauls and he will be sorely missed. We trust that Patrick O'Brien will prove his worth in this all important game."
O'Brien would partner veteran Ligtoring Landman to help bolster a Griquas scrum that would be targeted by the Pumas in Nepgen's absence.
In other tactical moves, Carel Greeff would come in at eighthman replacing flanker Marnus Schoeman, relegated to the bench.
Burger Schoeman would move from behind the scrum to flanker and, at the same time, switch sides with RJ Liebenberg.
Greeff impressed in last week's game as an impact player, in his first game since recovering from a broken hand. It was always expected Schoeman, who conceded too many penalties last week against the Pumas, would make way for him.
"We cannot afford to lose the game to the Pumas and, therefore, our discipline has to be top notch," Human said.
"We gave away silly penalties last week and they capitalised on that. If we don't limit our infringements it can cost us dearly."
In the only other change to the starting line up, Jacques Coetzee replaced Marnus Hugo, with the latter also dropping to the bench.
Prop Nick Schonert has been added to the bench to help bolster the scrums.
"We know that the Pumas are going to test us in the scrums and so we're glad Nick is also available. We pride ourselves in our scrumming and will look to be at our best in that facet."
Gouws Prinsloo, Willie le Roux, Jean Stemmet, Howard Mnisi, Rocco Jansen, Francois Brummer, Jacques Coetzee, Carel Greeff, RJ Liebenberg, Burger Schoeman, Patrick O'Brien, Ligtoring Landman, Lourens Adriaanse, Ryno Barnes (captain), Steph Roberts
Replacements: Matt Dobson, Janro van Niekerk, Nick Schonert, Marnus Schoeman, Marnus Hugo, JP Nel, Nico Scheepers.