The Springboks knocked France out of their home tournament in Paris in dramatic fashion in a game regarded as one of the best at a World Cup, and several French players have spoken of the devastating effect of that loss.
That will no doubt leave the home side desperate for revenge, and De Jager expects them to front up in the forwards and try to apply pressure on the Springboks at the set-piece.
"They are a very good team, and we know it’s going to be a very big challenge on Saturday, but we are looking forward to it," De Jager told reporters on Tuesday.
"They have a big pack and are generally very confrontational, so it’s going to be a big challenge for us to see where we are on Saturday.
"They have a good maul and scrum, and they play very direct rugby, so it is going to be a good test for our forwards."
De Jager is a master poacher at the lineout and says that will be a fascinating battle at the Stade de France.
"We analyse every team we play and obviously we’ve had a look at their lineouts," he said.
"They have a high success rate in that area of their game and a proper maul, and that’s definitely a threat, so we have to do our best to negate that if we want to get the upper hand to win the match."
Springbok coach Rassie Erasmus will name his team for the clash on Thursday.
South Africa defeated Japan 61-7 in London on the first game of their five-match tour last weekend.
They also take on Italy, Ireland and Wales as they seek to hold on to the number one world ranking ahead of the 2027 Rugby World Cup draw on December 3.