Du Preez hasn't played since the 2023 EPCR Challenge Cup final and was out for the whole of the 2023/24 season after a serious knee injury. After a long recovery period, Du Preez has been named among the Glasgow replacements bench to face the Welsh outfit.
Speaking to Scotland Rugby News, Glasgow head coach Franco Smith said: "It is a miracle. I'm really proud of the medical team and our S&C team that worked really hard. And then obviously JP.
"He had a big setback after he got hurt in training in August 2023. He had a normal procedure. He got a problem in the bone that had to be removed in the end. We had to get a donor bone for him. That had to be accepted by his body, not rejected. Then another set of rehab started.
"It's fantastic to get him out there. He's moving well. He's worked really, really hard. I don't think people realise how hard you've got to work to get a big body like that - 130kg, 7ft high - to move and be agile.
"This is the final part of his return to play. We're excited to have him back. More than once it felt like this was an irrecoverable injury. Again, we prayed about this a lot. The medical staff did a great job. He keeps believing in himself. He moves well. He moves as good as he moved before he got injured."